US20010046054A1 - System and method for performing selected optical measurements utilizing an optical coherence domain reflectometer - Google Patents
System and method for performing selected optical measurements utilizing an optical coherence domain reflectometer Download PDFInfo
- Publication number
- US20010046054A1 US20010046054A1 US09/772,340 US77234001A US2001046054A1 US 20010046054 A1 US20010046054 A1 US 20010046054A1 US 77234001 A US77234001 A US 77234001A US 2001046054 A1 US2001046054 A1 US 2001046054A1
- Authority
- US
- United States
- Prior art keywords
- sample
- reflections
- diffraction
- diffraction grating
- detector
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 0 C*(CC1C2)C(CCC3)C3CCOC2CC1C=C Chemical compound C*(CC1C2)C(CCC3)C3CCOC2CC1C=C 0.000 description 2
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/48—Other medical applications
- A61B5/4869—Determining body composition
- A61B5/4872—Body fat
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0062—Arrangements for scanning
- A61B5/0066—Optical coherence imaging
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0062—Arrangements for scanning
- A61B5/0068—Confocal scanning
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0073—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by tomography, i.e. reconstruction of 3D images from 2D projections
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
- G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/02007—Two or more frequencies or sources used for interferometric measurement
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/02012—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal intensity variation
- G01B9/02014—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal intensity variation by using pulsed light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/0209—Low-coherence interferometers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/0209—Low-coherence interferometers
- G01B9/02091—Tomographic interferometers, e.g. based on optical coherence
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4795—Scattering, i.e. diffuse reflection spatially resolved investigating of object in scattering medium
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0082—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes
- A61B5/0084—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes for introduction into the body, e.g. by catheters
Definitions
- the present invention relates generally to a method and system for making optical measurements and, more particularly, to a method and system for making optical measurements using optical coherence domain reflectometry.
- Optical coherence domain reflectometry a well-known technique, is based on detection of an interference signal and becomes an attractive method for making precision measurements that provide resolution of 10 ⁇ m and a dynamic range of more than 100 dB for depth scan up to few mm.
- OCDR Optical coherence domain reflectometry
- OCDR has been developed for imaging of the anterior eye and retina, optical tomography and histology in highly-scattering media, and catheter-endoscope tomography in internal organ systems.
- the mirror velocity is typically in the range of 30 mm/sec corresponding to a Doppler frequency of 50 kHz.
- Doppler frequency 50 kHz.
- a short coherence optical radiation source applies optical radiation through like optical paths to a sample and an optical reflector.
- the optical reflector is movable in accordance with a predetermined velocity profile to permit interferometric scanning of the sample, the resulting output having a Doppler shift frequency modulation.
- This output may be demodulated and detected to obtain desired measurements and other information.
- Additional information may be obtained by applying radiation from two or more sources at different wavelengths to the sample and reflector and by separately demodulating the resulting outputs before processing.
- Birefringent information may be obtained by polarizing the optical radiation used, by suitably modifying the polarization in the sample and reference paths and by dividing the output into orthogonal polarization outputs which are separately demodulated before processing.
- a detector for bringing said positive diffraction order and said negative diffraction order which are directed along said same path to focus on said detector, said detector producing an output of said positive diffraction order and said negative diffraction order received, and a computer for processing said output from said detector.
- a system for performing selected optical measurements on a sample comprises a broad band light source, a first beamsplitter for splitting light from said broad band light source into a signal beam and a reference beam, a reference mirror disposed along the path of the reference beam, the sample being disposed along the path of the signal beam, a first lens for bringing the signal beam to focus on said sample, a diffraction grating for receiving reflections from the reference mirror and producing therefrom a diffracted beam, the reflections from the reference mirror being incident on the diffraction grating such that a diffraction order from the reflections from the reference mirror is directed along a first path, a detector, a second beamsplitter for combining reflections from the sample with the diffraction order along said first path to produce a combined beam, a second lens for bringing said combined beam to focus on said detector, said detector producing an output of said combined beam received, and a computer for processing said output from said detector.
- a diffraction order from the signal beam is combined with reflections from the reference beam.
- a method for performing selected optical measurements on a sample comprises a method for performing selected optical measurements on a sample comprising providing a light source, splitting light form said light source into a signal beam and a reference beam, positioning a reference mirror along thee path of the reference beam, positioning the sample along the path of the signal beam, bringing the signal beam to focus on said sample, positioning a diffraction grating for receiving reflections from the sample and from the reference mirror and producing therefrom a diffracted beam, the reflections from the sample and the reference mirror being incident on the diffraction grating such that a positive diffraction order from the reflections from one of the sample and reference mirror and a negative diffraction order form the reflections from the other one of the sample and reference mirror are directed along the same path, the two diffraction orders being the same number i.e.
- both first order or both second order etc. providing a detector, bringing said positive diffraction order and said negative diffraction order directed along said same path to focus on said detector, said detector producing an output of said positive diffraction order and said negative diffraction order received, and processing said output from said detector.
- a method for performing selected optical measurements on a sample comprises providing a light source, splitting light from said light source into a signal beam and a reference beam, positioning a reference mirror along the path of the reference beam, positioning the sample along the path of the signal beam, bringing the signal beam to focus on said sample, positioning a diffraction grating for receiving reflections from the reference mirror and producing therefrom a diffracted beam, the reflections from the reference mirror being incident on the diffraction grating such that a diffraction order form the reflections from the reference mirror is directed along a first path, providing a detector, combining reflections from the sample with the diffraction order along said first path to produce a combined beam bringing said combined beam to focus on said detector, said detector producing an output of said combined beam received, and processing said output form said detector.
- the diffraction grating is stationary and the detector is a one dimensional linear CCD array while in other embodiments the diffraction grating is moving and the detector is a multichannel diode array whose output is fed into a demodulator.
- FIG. 1 is a schematic block diagram of one embodiment of a system for performing selected optical measurements of a sample constructed according to this invention
- FIG. 2 is a diagram illustrating the time delay grating-generated sample depth scan in the embodiment of the invention shown in FIG. 1;
- FIG. 3 is a cross-sectional view of a sample tested using the system shown in FIG. 1;
- FIG. 4 is a graph of the reflectance profile across the sample shown in FIG. 3 measured using the system shown in FIG. 1;
- FIG. 4( a ) is a CCD image of a single shot interference pattern
- FIG. 5 is a digitized cross correlation trace obtained using the system shown in FIG. 1;
- FIG. 6 is a schematic block diagram of another embodiment of a system for performing selected optic al measurements of a sample constructed according to this invention.
- FIG. 7 is a 2D interference image obtained using the system shown in FIG. 6;
- FIG. 8 is a schematic block diagram of a modification of the system shown in FIG. 6;
- FIG. 9 is a schematic block diagram of another modification of the system shown in FIG. 6;
- FIG. 10 is a schematic diagram useful in understanding another embodiment of the invention.
- FIG. 11 is a schematic block diagram of another embodiment of a system for performing selected optical measurements of a sample constructed according to this invention.
- FIG. 12 is a cross-sectional structure of an oil painting and an incident pulse impinging thereon;
- FIG. 13 is a schematic block diagram of a modification of a portion of the system shown in FIG. 11;
- FIG. 14 is a schematic block diagram of another modification of the system shown in FIG. 11;
- FIG. 15 is a schematic block diagram of another modification of the system shown in FIG. 11;
- FIG. 16 is a schematic block diagram of another modification of the system shown in FIG. 11;
- FIG. 17 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 18 is a schematic block diagram of a modification of the system shown in FIG. 17;
- FIG. 19 is a schematic block diagram of a modification of the system shown in FIG. 1;
- FIG. 20 is a schematic block diagram of a modification of the system shown in FIG. 11;
- FIG. 21 is a schematic block diagram of a modification of another embodiment of a system for performing selected optical measurements of a sample constructed according to this invention.
- FIG. 22 is a schematic block diagram of a modification of the system shown in FIG. 21;
- FIG. 23 is a schematic block diagram of a modification of the system shown in FIG. 22;
- FIG. 24 is a schematic block diagram of a modification of the system shown in FIG. 23;
- FIG. 25 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 26 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 27 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 28 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 29 is a schematic block diagram of another embodiment of the invention.
- FIG. 30 is a schematic block diagram of another embodiment of the invention.
- FIG. 31 is a schematic block diagram of another embodiment of the invention.
- FIG. 32 is a schematic block diagram of another embodiment of the invention.
- FIG. 33 are views of the diffraction grating in the embodiment shown in FIG. 32;
- FIG. 34 is a schematic block diagram of another embodiment of the invention.
- FIG. 35 is a schematic block diagram of another embodiment of the invention.
- FIG. 37 is a schematic block diagram of another embodiment of the invention.
- the present invention is directed to a multifunctional fast correlation-domain interferometric method and system for biomedical and nonmedical applications.
- the present invention involves single shot method of ultrafast correlation interferometry (UCI)I for imaging microscopic scale reflective objects.
- UCI ultrafast correlation interferometry
- the method converts the time propagating of pulses reflected from an object into a corresponding coherence-domain interference pattern that permits the simultaneous registration of reflections by use of a stationary diffraction grating and a one dimensional CCD array in some embodiments and in other embodiments by a moving diffraction grating and a multichannel diode array and demodulator.
- FIG. 1 an embodiment of a system constructed according to this invention and identified by reference numeral 11 .
- system 11 light from a colliding-pulse mode-locked laser 13 , is amplified in an amplifier apparatus 15 , reflected off a first mirror Ml and strikes a first beamsplitter BSI where it is split into a transmitted part which serves as a signal beam and reflected part which serves as a reference beam.
- Amplifier apparatus comprises a pair of movable mirrors MM 1 and MM 2 , a pair of fixed mirrors M 3 and M 4 and an amplifier system 21 .
- the reference beam passes through a neutral density filter ND and strikes a reference mirror M 5 .
- Light pulses from reference mirror M 5 pass back through neutral density filter ND, through first beamsplitter BSI and are incident on a reflection diffraction grating G.
- Grating G is oriented so as to have vertically disposed grooves.
- the signal beam transmitted through first beamsplitter BSI passes through a second beamsplitter BS 2 and is brought to focus by a spherical lens 01 on a sample S.
- Light pulses reflected from sample S are reflected off second beamsplitter BS 2 and are incident on grating G.
- the diffraction order from the reflections from sample S can either be a first order or a second order or a higher order.
- the diffraction order from the reflections from mirror M 5 is the same order (i.e. number) as the diffraction order of reflections from sample S.
- the diffracted light from the reference beam propagating along the normal to the diffraction grating is the negative first diffraction order and the diffracted light form the signal beam propagating along the normal to the diffraction grating is the positive first diffraction order.
- a lens L 1 collects the diffracted light and focuses the light onto a one dimensional CCD detector 23 placed at the conjugate image plane of grating G.
- CCD array 23 includes an input shutter (not shown) to allow the diffraction orders from only one pulse to pass through.
- the output of CCD detector 23 which corresponds to a depth scan i.e. a scan in the Z direction, is fed into a computer 25 where the output from CCD 23 is processed.
- the diffraction grating introduces a continuous optical delay between a reference pulse and a pulse reflected by a sample in the direction of the grating dispersion (x axis).
- pulses reflected by the front and back sample surfaces are split by the diffraction grating in x-direction so that interference maxima showing depth-scan reflections are also split in x-direction.
- the difference of optical path is
- ⁇ is the wavelength
- x is the linear coordinate
- T is the time delay between the reference and signal pulses.
- D is the diameter of the beams.
- ⁇ 620 nm
- p 1/1200 mm
- cos ⁇ 0.73
- a time-display window of T d 20 ps is achieved which corresponds to a sample depth of up to 3 mm on single measurement.
- the light source can be any broad band light source.
- the correlation approach of this invention was tested on measuring the thickness of the cladding of a single-mode fiber schematically shown in FIG. 3.
- the measured reflectance profile across the fiber is shown in FIG. 4.
- the ultrafast method of this invention has potential applications for noncontact diagnostics of reflective biological and medical structures to yield the histological picture of tissue because of it insensitivity to mechanical instability.
- Each reflective layer at depth z will be obtain as a signal to map its location.
- an interferometric system can be used for optical communications as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography.
- An accumulated photon echo read-out speed as fast as 27 Terabit per second was demonstrated using this singleshot crosscorrelation method for a femtosecond four-pulse packet stored by spectral hole burning in a octaethylporphine-doped polystyrene sample.
- FIG. 4 a demonstrates the crosscorrelation detection of an echo four-pulse packet on a single-shot basis.
- a CCD image of the single-shot interference pattern (between the recalled echo four-pulse packet and a cross-reference pulse) is displayed in FIG. 4 a and the corresponding digitized crosscorrelation trace is shown in FIG. 5.
- the echo pulses are separated by 1.7 psec.
- the interference pattern and crosscorrelation of the echo signals demonstrates the good single-shot reproduction of the temporal profile of the initial pulse packet and provides 4 bits of information per 150 fsec which corresponds to a data readout speed of 27 Terabit/sec.
- This invention can be used to produce an interference 2D (depth-transversal coordinate) image of biological tissue with acquisition time as short as 20 ms.
- This method of grating-generated interference microscopy called GIM is applied to produce a high resolution image of skin tissue.
- FIG. 6 A schematic diagram of an experimental system used to illustrate the invention for obtaining a 2D image is shown in FIG. 6 and identified by reference numeral 31 .
- System 31 differs from system 11 in that amplifier apparatus 15 is omitted, the light source is a Ti:Sapphire laser 33 rather than a CPM laser, L 2 is a cylindrical lens, O2 is an objective lens and CCD 34 is a 2D imaging array.
- the chicken skin tissue sample (about 3 mm of thickness) is attached to the glass plate (P) surface.
- the grating plane is optically conjugated with a 1024 ⁇ 1024 pixel CCD array by the lens L 2 which records the 2D interference image.
- the diffraction grating introduces a continuous optical delay (producing biological depth scan) in the direction of the grating dispersion (x axis).
- D 2.5 mm
- ⁇ 800 nm
- p 1 / 600 mm
- cos ⁇ 0.877
- a time-display window of T d 13.5 ps is achieved which corresponds to a sample depth scan of up to 2 mm.
- a second CCD exposure defined as a reference is applied for which interference between reference and signal pulses is destroyed.
- the dynamic range (DR) of GIM is defined by the ratio of the largest measurable CCD interference signal to the noise (SNR):
- W is the CCD camera detected signal, which is proportional to the light impinging at the CCD array and PS is the sample amplitude reflectivity.
- the dynamic range of GIM depends on the DR of the CCD array.
- the CCD camera with “ 14 bit DR” has a DR of approximately 1.6 ⁇ 10 4 / 1 , which leads to a potential dynamic range (DR) max of 80 dB.
- the sensitivity (S) of GIM is defined as:
- the maximum CCD output signal occurs when the amplitudes of reference and signal pulses are equal. Take into account that W W 2 max can be changed, introducing a neutral density filter in the reference beam then filter double-pass optical density (OD) ref is equal
- Equation (8) shows an important feature of GIM. S can be increased independently of the GIM DR.
- a 2D interference image (after subtraction of a signal and a reference images) of the chicken skin tissue is shown in FIG. 7.
- a rapid 20 ms acquisition time to acquire 2D image for laser power of 30 mw is achieved. This time is ten times faster than other methods.
- the transversal high resolution structures of the skin, a membrane and muscle are visualized for the depth of up to 1.5 mm.
- reference mirror M 5 is moved by a PZT transducer 35 into two positions with the path difference equal to ⁇ /2, where ⁇ is the source central wavelength.
- the positions of reference mirror M 5 is managed by a photodetector—PZT feedback loop 37 to acquire two images, one background+signal and the other background ⁇ signal, corresponding for the two positions of the PZT.
- FIG. 9 In order to increase the data acquisition speed and remove background the interferometric system can be constructed as shown in FIG. 9.
- the system in FIG. 9, which is identified by reference numeral 43 there is a focusing lens L 3 , acousto-optical modulator (AOM), a 90° reflection prism 45 , two neutral density filters ND and two reflection mirrors M 5 .
- Mirrors M 5 are located so that the beam deflected by modulator AOM and reflected by the sides of prism 45 and one of the mirrors M 5 is directed back to the diffraction grating G at the diffraction angle - ⁇ .
- the CCD frames with and without interference are subtracted sequentially one from another to produce a series of the 2D (depth- transversal coordinate) dark-field interference images.
- the remainder of system 43 is substantially identical to system 31 in FIG. 6.
- Another version of this invention utilizes the principal that when a light beam is diffracted by a moving diffraction grating ( DG ), the frequency of the diffracted light has a Doppler shift.
- DG moving diffraction grating
- the Doppler frequency shift (DFS) between diffracted reference and signal beams is
- System 51 includes a laser light source 53 , a first beamsplitter BSI, a second beamsplitter BS 2 , a grating DG, a reference mirror M 5 a translation 55 for moving grating DG, a focusing lens 01 , a collection lens L 1 , a multichannel diode array 57 , a demodulator 59 and a computer 61 .
- System 51 differs from system 31 mainly in that the grating is movable and that the detector is a multichannel diode array and a demodulator.
- the optical signal from grating DG i.e.
- the diffracted light is directed to multichannel linear array (L.A.) detector 57 .
- the optical signal is detected by demodulating the multichannel diode array detector 57 output at the Doppler shift frequency (DSF).
- DSF Doppler shift frequency
- the output signal W f (T) is given by:
- This method performs high-resolution cross-sectional imaging by illuminating tissue with low-coherence light and measuring the back scattered light as a function of grating-generated time delay or range at different transverse positions.
- the sample S is mounted on a stage (not shown) which is movable by means (not shown) in the “X” and “Y” directions so as to provide 3D imaging.
- the system in FIG. 11 provides a noncontact, high-sensitivity, high-resolution technique for optical imaging.
- High scan speeds are especially relevant for medical and biological diagnostic applications. Histological architecture of eye and tissue is of special interest is the noninvasive measurement of anterior eye dimensions and tissue diagnosis.
- high-speed grating-generated depth scan has numerous applications for noncontact diagnostics of precision mechanical and optical systems as well as for process control and monitoring in manufacturing.
- Intravascular ultrasound is an existing catheter-based technique for obtaining cross-sectional images of human vasculature.
- the technique of this invention has the capability to image vascular lesions with much higher resolution and may be clinically useful for performing high-resolution imaging of other organ system, such as the artery, skin or GYN, GI tract or bladder.
- FIG. 12 A diagram to illustrate the typical cross-sectional structure of an oil painting is shown in FIG. 12, where (A) is particulate dirt deposits, (B) is varnish layer; (C) paint layer (pigment particles in a drying oil medium); (D) ground layer (lead white in a drying oil medium); Canvas support (usually linen) impregnated with size (usually animal glue).
- the incident pulse is reflected by these layers.
- the time delay between reflected pulses and pulse intensity consist information about the layers depth and reflectivity. This information can be extracted using the interferometric system of this invention.
- the DFS between diffracted reference and signal beams can be also obtained if the DG is shaken along its plane as shown by arrow B by a piezotransducer (PZT) so that grating displacement is more than the grating groove space (See FIG. 13).
- PZT piezotransducer
- the acquisition speed is increased by using a diffraction grating that is rotating at a constant angle speed ⁇ .
- Increasing of the grating tangential speed Vt is achieved in system 71 shown in FIG. 14.
- grating DG is attached by an arm 73 (not shown) to the drive shaft 75 of a motor (not shown).
- the AC signal processing time of the each diode array pitch is about 10/8 ⁇ 10 7 ⁇ 0.1 ⁇ s.
- the time response of 0.1 ⁇ s for each axial scan and scan repetition rates (SRR) of 100 l.p./s can be realized.
- One way to increase the data acquisition speed is to increase the SRR use several diffraction gratings disposed on the sides of a multisided cylindrical device (See FIG. 15). These grating are rotated around the longitudinal axis of the device and the signal beam is discretely scanning in the x (or y) direction so that position of each rotating grating is synchronized with a certain x (or y) position of the scanning system. About 30 gratings of the 1 cm length can be used for the circle radius of 5 cm. The SRR is 3 ⁇ 10 3 l.p./s.2). If the diffraction grating is carried on cylindrical surface CS rotating with constant angle speed the maximum of the SRR and the lateral resolution can be realized (See FIG. 16).
- the SRR is 1 Mhz for 0.1 ⁇ s axial scan time response.
- the interference image output is collected by the fiber linear array FLA (See FIG. 17).
- Each fiber output is connected with a certain diode array pitch.
- the size of the each L.A. diode pitch is of 1 mm.
- the diameter of the single-mode fiber is about 100 ⁇ m and the tenfold increasing of the axial resolution can be achieved.
- the diffraction grating and fiber linear array connected with the multichannel photodetector are mounted on a fast moving translator (see FIG. 18).
- the light source one is an array of diode lasers LA, each emitting light at different wavelength ⁇ , according to relation ( 2 ).
- the LA laser source is mounted on a holder, accommodating y (or x) translational stage.
- the position of one laser diode is synchronized with the position of one diffraction grating.
- the wavelength is selected for the maximum depth exposure typically from 600 to 1600 nm.
- a rotating diffraction grating DG with a vertical extension in the form of a reflecting mirror ME is used as shown in system 73 in FIG. 21.
- the diffracted beams are reflected from a stationary spherical mirror SM which displaces these beams in the vertical direction and directs them back to the rotating reflection mirror ME.
- Beams reflected from rotating mirror ME are directed into a vertical slit VS.
- the slit plane is optically conjugated with the grating plane by the reflecting spherical mirror SM.
- Optical signal passing the slit is detected by demodulating the single detector output at the Doppler shift frequency between signal and reference beams produced by rotating grating RG.
- the diffracted signal and reference beams are reflected from a small angle shaking reflection mirror SRM as shown in system 75 in FIG. 22.
- SASM small angle shaking mechanism for shaking the diffraction grating which is carried on a spherical (or cylindrical) reflection surface with the vertical extension by the reflecting mirror.
- the axes of a small angle shaking are passing through the center of the grating spherical (or cylindrical) reflection surface (see FIG. 23).
- the interferometric system can be performed so that beams reflected from the shaking (or rotation) grating are directed to the shaking (or rotation) reflection mirror SRM placed at the axes of shaking (or rotation) of the grating and after mirror reflection are directed to a stationary fiber array connected with the multichannel photodetector (see system 77 in FIG. 24).
- the signal and reference interferometer arms are fiber-coupled as shown in system 79 in FIG. 25. Tissue reflectance is obtained axially by the grating-generated depth scan and digitizing the magnitude of the demodulated interference envelope.
- the input of the signal beam fiber is connected with a catheter and the fiber output is connected with a lens LEI which directs the signal beam to the grating at the diffraction angle ⁇ .
- the fiber output of the reference beam is connected with a lens LE 2 which directs the reference beam to the grating at the diffraction angle ⁇ . Fiber optics allow to improve the flexibility of the interferometer set up.
- the catheter is designed to scan the beam in a circumferential pattern to image cross sectionally through the vessel (or other biological structure) into which it is inserted.
- image acquisition the catheter is inserted into the tissue structure being imaged (the artery or other internal tissue channel), and, as the drive motor (not shown) turns, the shaft of the catheter and the distal optics circumferentially scan the focused beam perpendicular to the axis of the catheter.
- An image is acquired as the beam angle of rotation is varied over some range (usually 360 deg).
- the speed of imaging depends on the speed of the rotation and the proposed interferometer acquisition speed.
- This interferometric system can be used for optical communications as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography (see system 81 in FIG. 26).
- an optical memory system for example, hole-burning holography
- This interferometric system can be used for optical communications as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography (see system 81 in FIG. 26).
- hole-burning holography see system 81 in FIG. 26.
- a pulse code signal is directed on the grating at the diffraction angle ⁇ and a coherent reference pulse is directed on grating at the diffraction angle ⁇ .
- the pulse code For time-display window of 20 ps and the pulse amplitude correlation time of 100 fs the pulse code has about 2 10 3 bit.
- the information reading speed is of 2 10 9 bits/s with 1 MHz repetition rates for 1 ⁇ s axial scan time response.
- the SNR is about 100 dB.
- Ultrafast time-domain data packets can be created by the filtering of mode-locked laser pulses. Efficient detection of ultrashort time-domain signals requires novel receiver systems.
- the proposed interferometer can be performed as a receiver of a pulse code signal, received from the optical communication system (OCS) (see system 83 in FIG. 27). The pulse code signal is directed on the grating at the diffraction angle a and coherent reference pulse extracted from OCS is directed on grating at the diffraction angle ⁇ .
- OCS optical communication system
- the development of sub-picosecond laser sources has largely precluded techniques for accurate and complete characterization of pulses coming from such lasers.
- the spectral phase of femtosecond pulse can be measured using a frequency domain correlator. This technique involves cross correlating different spectral slices of the original pulse with itself. The relative delay of the spectral components with respect to each other provides information about any chirp which may be present.
- the interferometer can be performed so that signal beam includes zero-dispersion stretcher with moving slit placed in the stretcher spectral plane to measure dependence of the output signal position on the slit position (see system 85 in FIG. 28). These measurements allow a person to obtain the spectral phase of the input pulse increasing measurement sensitivity and acquisition speed.
- signal and reference beams are focused by the combination of the cylindrical lenses into the narrow line on the surfaces of a grating and the 2D CCD array. Position of this narrow line is changed on the CCD array, for example, in vertical direction by a rotating mirror so that each lateral position of the signal beam produces the vertical shifted narrow line image on the CCD array.
- Several depth-lateral digital images are recorded with different phase shifts. These images are digital processing to produce a 3D image.
- the signal to noise ratio is increased using an interferometric system wherein the signal and reference beams are focused into a diffraction grating.
- the optical output signal is detected by demodulating the single detector output at the Doppler shift frequency.
- the interferometric system is constructed so that a linear source image on the surface of the sample can be rotated, for example, by 90 degrees.
- a PZT stretched fiber is inserted to produce phase modulation.
- Several depth-lateral digital images are recorded by a 2D imaging CCD array with different phase shifts. These images are digital processing to produce a 3D image of the internal structure of a sample.
- two perpendicular linear sources illuminate a sample simultaneously.
- Two diffraction gratings with perpendicular orientations of the grooves are used to create simultaneously two images on two CCD arrays to produce signals for a 3D image processing of the internal structure of a sample.
- one or two CCD arrays are used to produce images in x or y directions in combination with the axial z scans of the depth of a sample along the grating dispersion.
- the images produced by the CCD arrays are used to create a 3D image of a sample.
- System 101 includes an SLD light source 102 , a pair of beamsplitters 103 and 104 , a three lens 105 , and 106 and 107 a rotating diffraction grating 107 , a stretcher, 108 , a mirror 109 , a detector 110 , electronics 111 and a computer 112 .
- FIG. 32 A further embodiment of the invention is shown in FIG. 32 and a view of the diffraction grating in the system in FIG. 32 is shown in FIG. 33.
- FIG. 34 there is shown another embodiment of the invention identified by reference numeral 121 .
- a diffracted reference beam is combined with reflections from a sample.
- Diffraction grating DG is angled relative to the reference beam so that one of said first or second or higher diffraction orders from the light strikes the diffraction grating from the reference beams, either positive or negative is normal to the diffraction grating DG.
- As the diffracted reference beam is combined with reflections from sample S by a second beamsplitter BS 2 .
- the combined beam is brought to focus into detector DET by a lens L 1 .
- the output of detective DET is fed into a computer COMP.
- FIG. 35 there is shown another embodiment of the invention identified by reference numeral 131 .
- System 131 differs from sytstem 121 in that diffraction grating DG is angled relative to the reference beam such that the reference beam is normal to the diffraction grating DG and the diffracted reference beam (either the first, second or higher order, and either positive or negative) that is combined with reflections from the sample is not normal to diffraction grating DG.
- System 131 shown in FIG. 36 differs from system 121 in that the reference beam is not normal to diffraction grating DG.
- System 141 shown in FIG. 37 differs from system 131 in that the first beamsplitter BS 1 and the reference mirror M 5 are eliminated. Instead, beamsplitter BS 2 is used to produce a reference beam which strikes diffraction grating DG to produce a diffracted beam which is combined with reflections from the sample beam and sample beam which strikes the sample.
- the positive and the negative first-order diffracted signal and reference beams propagate along the normal to the grating.
- the diffraction grating introduces a continuous optical delay between the reference pulses and pulses reflected by the sample in the direction of the grating dispersion (x axis).
- pulses reflected by the surfaces located inside the sample are split by the diffraction grating in x-direction so that interference maxima showing depthscan reflections are also split in x-direction that permits the simultaneous registration of reflections using a CCD array.
- Each reflective layer at depth z i will be obtain as a signal to map its location.
- the reference interferometer arm comprises a reflection mirror movable to the two different positions with a path difference more than grating time-display window (T d ⁇ 20 ps) and a variable neutral-density filter.
- PZT stretched fiber can be inserted to create the delay time more than T d .
- a signal arm comprises a convex cylindrical (spherical) lens or their combination, to create, for example, a linear source image on the surface of the sample, and registration system. Two images are obtained.
- a 2D imaging CCD array acquires two images sequentially with (signal) and without (reference) interference corresponding for two different positions of the reference mirror. These signal and reference images are computer subtracted to produce a 2D (depth-transversal coordinate) dark-field interference image.
- the interferometric system is performed using a reference arm comprising a focusing lens, acousto-optical modulator (AOM), 90° reflection prism, two reflection mirrors placed against the prism reflection sides so that the beam deflected by the AOM and reflected by the one of the prism side and one of the mirrors is directed back to the diffraction grating at the diffraction angle ⁇ .
- CCD frames with and without interference are subtracted sequentially one from another to produce a series of the 2D (depth- transversal coordinate) dark-field interference images.
- the interferometric system includes a diffraction grating is moving along its plane with constant speed producing a Doppler shift frequency between signal and reference beams.
- the optical signal is detected by demodulating a multichannel linear array (LA) detector output at the Doppler shift frequency.
- LA multichannel linear array
- the diffraction grating is along its plane using, for example, a piezotransducer (PZT) so that grating displacement is more than the grating groove space.
- PZT piezotransducer
- each fiber output is connected with a certain diode array pitch.
- a diffraction grating comprising a composition of the several co-plane diffraction gratings with different spacing between grooves.
- laser source is a linear array of the laser sources of different wavelengths ⁇ (400 to 600 nm).
- the laser source array is mounted on a holder, accommodating x (or y) translational stage allow to choose appropriate wavelength of the laser source.
- the interferometric system uses laser sources adapted to emit at second harmonics.
- beams reflected from a shaking (or rotation) grating are directed to a shaking (or rotation) reflection mirror placed at the axes of shaking (or rotation) of the grating and after mirror reflection are directed to a stationary fiber array connected to a multichannel photodetector.
- the interferometric system in a PZT shaking DG signal and reference beams are reflected from a small angle shaking reflection mirror. Beams reflected from the shaking mirror are directed into a vertical slit. Optical signal passing the slit is detected by demodulating the single detector output at the Doppler shift frequency.
- the diffraction grating is formed on the spherical (or cylindrical) reflection surface with a vertical extension reflecting mirror which is shaken over a small angle.
- the axes of the small angle shaking is passing through the center of the grating spherical (or cylindrical) reflection surface.
- the signal and reference interferometer arms are fiber-coupled.
- the input of the signal beam fiber is connected for example with a catheter and the fiber output is connected with a lens which directs the signal beam to the grating at a diffraction angle a.
- the fiber output of the reference beam is connected with a lens which directs the reference beam to the grating at the diffraction angle ⁇ .
- interferometric system as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography.
- the pulse code signal is directed on the grating at the diffraction angle a and coherent reference pulse is directed on grating at the diffraction angle ⁇ .
- An interferometric system having a signal beam which includes a zero-dispersion stretcher with moving slit placed in the stretcher spectral plane to measure dependence of the output signal position on the slit position. These measurements allow obtaining the spectral phase of the input pulse.
Abstract
Description
- This application is a continuation of U.S. patent application Ser. No. 09/378,846 filed on Aug. 23, 1999, which is a continuation-in-part of U.S. patent application Ser. No. 08/984,879 filed on Dec. 4, 1997 (now U.S. Pat. No. 5,943,133), which claims the benefit of U.S. provisional patent application Ser. No. 60/033,220 filed on Dec. 4, 1996, and U.S. provisional patent application Ser. No. 60/042,489 filed on Apr. 2, 1997, all of which patent applications are incorporated herein by reference.
- The present invention relates generally to a method and system for making optical measurements and, more particularly, to a method and system for making optical measurements using optical coherence domain reflectometry.
- Optical coherence domain reflectometry (OCDR), a well-known technique, is based on detection of an interference signal and becomes an attractive method for making precision measurements that provide resolution of 10 μm and a dynamic range of more than 100 dB for depth scan up to few mm. Using a high speed linear translation stage, OCDR measurements can be performed at modest high speeds. This method can be used to determine an internal depth image below the surface. OCDR has been developed for imaging of the anterior eye and retina, optical tomography and histology in highly-scattering media, and catheter-endoscope tomography in internal organ systems. The mirror velocity is typically in the range of 30 mm/sec corresponding to a Doppler frequency of 50 kHz. To achieve ultrahigh image acquisition speeds alternative technologies to mirror-translation scanning must be developed.
- In U.S. Pat. 4,459,570 issued on Oct. 17, 1995 to E.A. Swanson et. al, a method and apparatus for performing various optical measurements is provided utilizing an optical coherence domain refractometer (OCDR). A short coherence optical radiation source applies optical radiation through like optical paths to a sample and an optical reflector. The optical reflector is movable in accordance with a predetermined velocity profile to permit interferometric scanning of the sample, the resulting output having a Doppler shift frequency modulation. This output may be demodulated and detected to obtain desired measurements and other information. Additional information may be obtained by applying radiation from two or more sources at different wavelengths to the sample and reflector and by separately demodulating the resulting outputs before processing. Birefringent information may be obtained by polarizing the optical radiation used, by suitably modifying the polarization in the sample and reference paths and by dividing the output into orthogonal polarization outputs which are separately demodulated before processing.
- Another reference of interest is U.S. Pat. No. 5,491,552 issued on Feb. 13,1996 to A. Knuttel.
- It is an object of this invention to provide a new and improved method and system for optically performing high resolution measurements.
- It is another object of this invention to provide a new and improved method and system for optically performing high resolution measurements using a diffraction grating.
- It is another object of this invention to provide a method and system for obtaining a 2D image of a sample without scanning the sample in the lateral direction.
- It is a further object of this invention to provide a method and system for obtaining a 3D image of a sample.
- A system for performing selected optical measurements on a sample constructed according to the teachings of certain embodiments of this invention comprises a broad band light source, a beamsplitter for splitting light from said broad band light source into a signal beam and a reference beam, a reference mirror disposed along the path of the reference beam, the sample being disposed along the path of the signal beam, a first lens for bringing the signal beam to focus on said sample, a diffraction grating for receiving reflections from the sample and from the reference mirror and producing therefrom a diffracted beam, the reflections from the sample and the reference mirror being incident on the diffraction grating such that a positive diffraction order from the reflections from one of the sample and reference mirror and a negative diffraction order from the reflections form the other one of the sample and reference mirror are directed along the same path, the number of the two diffraction orders being the same, i.e. both first order or both second order etc., a detector, a second lens for bringing said positive diffraction order and said negative diffraction order which are directed along said same path to focus on said detector, said detector producing an output of said positive diffraction order and said negative diffraction order received, and a computer for processing said output from said detector.
- A system for performing selected optical measurements on a sample according to other embodiments of the invention comprises a broad band light source, a first beamsplitter for splitting light from said broad band light source into a signal beam and a reference beam, a reference mirror disposed along the path of the reference beam, the sample being disposed along the path of the signal beam, a first lens for bringing the signal beam to focus on said sample, a diffraction grating for receiving reflections from the reference mirror and producing therefrom a diffracted beam, the reflections from the reference mirror being incident on the diffraction grating such that a diffraction order from the reflections from the reference mirror is directed along a first path, a detector, a second beamsplitter for combining reflections from the sample with the diffraction order along said first path to produce a combined beam, a second lens for bringing said combined beam to focus on said detector, said detector producing an output of said combined beam received, and a computer for processing said output from said detector.
- In other versions of the invention a diffraction order from the signal beam is combined with reflections from the reference beam.
- A method for performing selected optical measurements on a sample according to certain embodiments of this invention comprises a method for performing selected optical measurements on a sample comprising providing a light source, splitting light form said light source into a signal beam and a reference beam, positioning a reference mirror along thee path of the reference beam, positioning the sample along the path of the signal beam, bringing the signal beam to focus on said sample, positioning a diffraction grating for receiving reflections from the sample and from the reference mirror and producing therefrom a diffracted beam, the reflections from the sample and the reference mirror being incident on the diffraction grating such that a positive diffraction order from the reflections from one of the sample and reference mirror and a negative diffraction order form the reflections from the other one of the sample and reference mirror are directed along the same path, the two diffraction orders being the same number i.e. both first order or both second order etc. providing a detector, bringing said positive diffraction order and said negative diffraction order directed along said same path to focus on said detector, said detector producing an output of said positive diffraction order and said negative diffraction order received, and processing said output from said detector.
- A method for performing selected optical measurements on a sample according to other embodiments of the invention comprises providing a light source, splitting light from said light source into a signal beam and a reference beam, positioning a reference mirror along the path of the reference beam, positioning the sample along the path of the signal beam, bringing the signal beam to focus on said sample, positioning a diffraction grating for receiving reflections from the reference mirror and producing therefrom a diffracted beam, the reflections from the reference mirror being incident on the diffraction grating such that a diffraction order form the reflections from the reference mirror is directed along a first path, providing a detector, combining reflections from the sample with the diffraction order along said first path to produce a combined beam bringing said combined beam to focus on said detector, said detector producing an output of said combined beam received, and processing said output form said detector.
- In some embodiments, the diffraction grating is stationary and the detector is a one dimensional linear CCD array while in other embodiments the diffraction grating is moving and the detector is a multichannel diode array whose output is fed into a demodulator.
- Various features and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawings which form a part thereof, and in which is shown by way of illustration, specific embodiments for practicing the invention. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing form the scope of the invention. The following detailed description is therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.
- In the drawings wherein like reference characters represent like parts:
- FIG. 1 is a schematic block diagram of one embodiment of a system for performing selected optical measurements of a sample constructed according to this invention;
- FIG. 2 is a diagram illustrating the time delay grating-generated sample depth scan in the embodiment of the invention shown in FIG. 1;
- FIG. 3 is a cross-sectional view of a sample tested using the system shown in FIG. 1;
- FIG. 4 is a graph of the reflectance profile across the sample shown in FIG. 3 measured using the system shown in FIG. 1;
- FIG. 4(a) is a CCD image of a single shot interference pattern;
- FIG. 5 is a digitized cross correlation trace obtained using the system shown in FIG. 1;
- FIG. 6 is a schematic block diagram of another embodiment of a system for performing selected optic al measurements of a sample constructed according to this invention;
- FIG. 7 is a 2D interference image obtained using the system shown in FIG. 6;
- FIG. 8 is a schematic block diagram of a modification of the system shown in FIG. 6;
- FIG. 9 is a schematic block diagram of another modification of the system shown in FIG. 6;
- FIG. 10 is a schematic diagram useful in understanding another embodiment of the invention;
- FIG. 11 is a schematic block diagram of another embodiment of a system for performing selected optical measurements of a sample constructed according to this invention.
- FIG. 12 is a cross-sectional structure of an oil painting and an incident pulse impinging thereon;
- FIG. 13 is a schematic block diagram of a modification of a portion of the system shown in FIG. 11;
- FIG. 14 is a schematic block diagram of another modification of the system shown in FIG. 11;
- FIG. 15 is a schematic block diagram of another modification of the system shown in FIG. 11;
- FIG. 16 is a schematic block diagram of another modification of the system shown in FIG. 11;
- FIG. 17 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 18 is a schematic block diagram of a modification of the system shown in FIG. 17;
- FIG. 19 is a schematic block diagram of a modification of the system shown in FIG. 1;
- FIG. 20 is a schematic block diagram of a modification of the system shown in FIG. 11;
- FIG. 21 is a schematic block diagram of a modification of another embodiment of a system for performing selected optical measurements of a sample constructed according to this invention,
- FIG. 22 is a schematic block diagram of a modification of the system shown in FIG. 21;
- FIG. 23 is a schematic block diagram of a modification of the system shown in FIG. 22;
- FIG. 24 is a schematic block diagram of a modification of the system shown in FIG. 23;
- FIG. 25 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 26 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 27 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 28 is a schematic block diagram of a modification of the system shown in FIG. 16;
- FIG. 29 is a schematic block diagram of another embodiment of the invention;
- FIG. 30 is a schematic block diagram of another embodiment of the invention;
- FIG. 31 is a schematic block diagram of another embodiment of the invention;
- FIG. 32 is a schematic block diagram of another embodiment of the invention;
- FIG. 33 are views of the diffraction grating in the embodiment shown in FIG. 32;
- FIG. 34 is a schematic block diagram of another embodiment of the invention;
- FIG. 35 is a schematic block diagram of another embodiment of the invention;
- FIG. 36 is a schematic block diagram of another embodiment of the invention; and
- FIG. 37 is a schematic block diagram of another embodiment of the invention.
- The present invention is directed to a multifunctional fast correlation-domain interferometric method and system for biomedical and nonmedical applications. The present invention involves single shot method of ultrafast correlation interferometry (UCI)I for imaging microscopic scale reflective objects. The method converts the time propagating of pulses reflected from an object into a corresponding coherence-domain interference pattern that permits the simultaneous registration of reflections by use of a stationary diffraction grating and a one dimensional CCD array in some embodiments and in other embodiments by a moving diffraction grating and a multichannel diode array and demodulator.
- Referring now to the drawings, there is shown in FIG. 1 an embodiment of a system constructed according to this invention and identified by reference numeral11.
- In system11, light from a colliding-pulse mode-locked
laser 13, is amplified in anamplifier apparatus 15, reflected off a first mirror Ml and strikes a first beamsplitter BSI where it is split into a transmitted part which serves as a signal beam and reflected part which serves as a reference beam. Amplifier apparatus comprises a pair of movable mirrors MM1 and MM2, a pair of fixed mirrors M3 and M4 and anamplifier system 21. - The reference beam passes through a neutral density filter ND and strikes a reference mirror M5. Light pulses from reference mirror M5 pass back through neutral density filter ND, through first beamsplitter BSI and are incident on a reflection diffraction grating G. Grating G is oriented so as to have vertically disposed grooves.
- The signal beam transmitted through first beamsplitter BSI, passes through a second beamsplitter BS2 and is brought to focus by a
spherical lens 01 on a sample S. Light pulses reflected from sample S are reflected off second beamsplitter BS2 and are incident on grating G. - The reflections from sample S and mirror M5 are incident on the grating with respect to grating normal so that a positive diffraction orders from the reflections from one of the sample S and mirror M5 and a negative diffraction order from the reflections from the other one of the sample S and Mirror M5 propagate along the normal (p sin α=λ, where p is the spacing between grooves, 1/1200 mm). The diffraction order from the reflections from sample S can either be a first order or a second order or a higher order. Similarly, the diffraction order from the reflections from mirror M5 is the same order (i.e. number) as the diffraction order of reflections from sample S.
- As an example, the diffracted light from the reference beam propagating along the normal to the diffraction grating is the negative first diffraction order and the diffracted light form the signal beam propagating along the normal to the diffraction grating is the positive first diffraction order.
- A lens L1 collects the diffracted light and focuses the light onto a one
dimensional CCD detector 23 placed at the conjugate image plane of gratingG. CCD array 23 includes an input shutter (not shown) to allow the diffraction orders from only one pulse to pass through. The output ofCCD detector 23, which corresponds to a depth scan i.e. a scan in the Z direction, is fed into acomputer 25 where the output fromCCD 23 is processed. - An explanation of the time delay grating-generated sample depth scan according to this invention may be better understood with reference to FIG. 2. As can be seen in FIG. 2, the diffraction grating introduces a continuous optical delay between a reference pulse and a pulse reflected by a sample in the direction of the grating dispersion (x axis). In this case, pulses reflected by the front and back sample surfaces are split by the diffraction grating in x-direction so that interference maxima showing depth-scan reflections are also split in x-direction. The difference of optical path is
- Δ=CT=2x sinα=2λx/p, (1)
- where λ, is the wavelength, x is the linear coordinate, and T is the time delay between the reference and signal pulses. The time-display window is given by
- T=2λD/cpcosα, (2)
- where D is the diameter of the beams. For an arrangement wherein D=3 mm, λ=620 nm, p=1/1200 mm, cosα=0.73 and a time-display window of Td=20 ps is achieved which corresponds to a sample depth of up to 3 mm on single measurement.
- Instead of a CPM laser the light source can be any broad band light source.
- The correlation approach of this invention was tested on measuring the thickness of the cladding of a single-mode fiber schematically shown in FIG. 3. The measured reflectance profile across the fiber is shown in FIG. 4. The refractive indices of the core (nc, =1.492) and the cladding (ncl=1.417) were used to determine the reflectivity of the corecladding boundary to be −3 3 dB and the cladding-air boundary to be −15 dB. The cladding thickness d of 19 μm (d=Δ/2ncl is distance into sample, Δ is optical delay) was determined.
- This system is also described in an article by I. Zeylikovich and R. R. Alfano in Optics Letters Vol. 21, No. 20 Oct. 15, 1996 pp. 1682-1684, which article is incorporated herein by reference.
- The ultrafast method of this invention has potential applications for noncontact diagnostics of reflective biological and medical structures to yield the histological picture of tissue because of it insensitivity to mechanical instability. Each reflective layer at depth z will be obtain as a signal to map its location.
- As will hereinafter be shown, an interferometric system according to this invention can be used for optical communications as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography. An accumulated photon echo read-out speed as fast as 27 Terabit per second was demonstrated using this singleshot crosscorrelation method for a femtosecond four-pulse packet stored by spectral hole burning in a octaethylporphine-doped polystyrene sample.
- FIG. 4a demonstrates the crosscorrelation detection of an echo four-pulse packet on a single-shot basis. A CCD image of the single-shot interference pattern (between the recalled echo four-pulse packet and a cross-reference pulse) is displayed in FIG. 4a and the corresponding digitized crosscorrelation trace is shown in FIG. 5. The echo pulses are separated by 1.7 psec. The interference pattern and crosscorrelation of the echo signals demonstrates the good single-shot reproduction of the temporal profile of the initial pulse packet and provides 4 bits of information per 150 fsec which corresponds to a data readout speed of 27 Terabit/sec.
- This invention can be used to produce an
interference 2D (depth-transversal coordinate) image of biological tissue with acquisition time as short as 20 ms. This method of grating-generated interference microscopy called GIM is applied to produce a high resolution image of skin tissue. - A schematic diagram of an experimental system used to illustrate the invention for obtaining a 2D image is shown in FIG. 6 and identified by
reference numeral 31.System 31 differs from system 11 in thatamplifier apparatus 15 is omitted, the light source is a Ti:Sapphire laser 33 rather than a CPM laser, L2 is a cylindrical lens, O2 is an objective lens andCCD 34 is a 2D imaging array. The chicken skin tissue sample (about 3 mm of thickness) is attached to the glass plate (P) surface. The signal beam is focused by the lens O (f=5 cm) onto the surface of glass plate P so that the beam spot size on the chicken skin surface is about 0.3 mm which determines the transversal coordinate image. The grating plane is optically conjugated with a 1024×1024 pixel CCD array by the lens L2 which records the 2D interference image. - The diffraction grating introduces a continuous optical delay (producing biological depth scan) in the direction of the grating dispersion (x axis). For the experimental arrangement described above, D=2.5 mm, λ=800 nm, p=1/600 mm, cosα=0.877 and a time-display window of Td=13.5 ps is achieved which corresponds to a sample depth scan of up to 2 mm.
- After CCD registration of the first interference pattern defined as a signal, a second CCD exposure defined as a reference is applied for which interference between reference and signal pulses is destroyed.
- The dynamic range (DR) of GIM is defined by the ratio of the largest measurable CCD interference signal to the noise (SNR):
- DR=10LOG(SNR). (3)
- There are several noise sources such as the readout CCD system noise (in the dark), optical measurements noise:
- SNR=W2 max/W2 min=(Psj)2 max/(Psj)2 min (4)
- where W is the CCD camera detected signal, which is proportional to the light impinging at the CCD array and PS is the sample amplitude reflectivity. The dynamic range of GIM depends on the DR of the CCD array. The SNR of the CCD camera is equal to the ratio (Wmax/W min), then (DR) max=(DR)2 ccd. The CCD camera with “14 bit DR” has a DR of approximately 1.6×104/1, which leads to a potential dynamic range (DR)max of 80 dB.
- The sensitivity (S) of GIM is defined as:
- S=10log[(Psj)2 min]. (5)
- Using Eqs. (3 to 5), the sensitivity of GIM is expressed as:
- S=10 log [(Psj)2 max]−DR (6)
- The maximum CCD output signal occurs when the amplitudes of reference and signal pulses are equal. Take into account that WW 2 max can be changed, introducing a neutral density filter in the reference beam then filter double-pass optical density (OD)ref is equal
- (OD)ref=−log[(Psj)2 max]. (7)
- Using Eq.(6 and 7) the sensitivity can be expressed by:
- S=−10(OD)ref−DR. (8)
- Equation (8) shows an important feature of GIM. S can be increased independently of the GIM DR. For our setup (Psj)2 min=10 −10, DR≈70 dB, and Eq.(8), (OD)ref is calculated to be 3.
- A 2D interference image (after subtraction of a signal and a reference images) of the chicken skin tissue is shown in FIG. 7.
- A rapid 20 ms acquisition time to acquire 2D image for laser power of 30 mw is achieved. This time is ten times faster than other methods. The transversal high resolution structures of the skin, a membrane and muscle are visualized for the depth of up to 1.5 mm.
- Another way to increase the system sensitivity and dynamic range of the interferometric system is shown in
system 33 in FIG. 8. Insystem 33, reference mirror M5 is moved by a PZT transducer 35 into two positions with the path difference equal to λ/2, where λ is the source central wavelength. The positions of reference mirror M5 is managed by a photodetector—PZT feedback loop 37 to acquire two images, one background+signal and the other background−signal, corresponding for the two positions of the PZT. Feedback loop 37 comprises a driver 39 and a photodetector 41. These two images are subtracted to produce 2D (depth-transversal coordinate) dark-field interference image with double sensitivity. In this way the background is removed and the signal is doubled. (Background+signal)−(background−signal )=Two times the signal. - In order to increase the data acquisition speed and remove background the interferometric system can be constructed as shown in FIG. 9. In the system in FIG. 9, which is identified by
reference numeral 43, there is a focusing lens L3, acousto-optical modulator (AOM), a 90°reflection prism 45, two neutral density filters ND and two reflection mirrors M5. Mirrors M5 are located so that the beam deflected by modulator AOM and reflected by the sides ofprism 45 and one of the mirrors M5 is directed back to the diffraction grating G at the diffraction angle -α. The CCD frames with and without interference are subtracted sequentially one from another to produce a series of the 2D (depth- transversal coordinate) dark-field interference images. The remainder ofsystem 43 is substantially identical tosystem 31 in FIG. 6. - For the grating-generated coherent scans with single-shot pulses the time response of the CCD linear array - computer memory is 1 ms. The repetition rates cannot be better than10 3 l.p./s. (Lateral pixels per second). As can be appreciated, a reference pattern is needed for each axial scan to reduce the background. Full axial scan needs at least 2 ms with repetition rates of 500 l.p/s. Using the repetition rates of 500 l.p/s and the artery scan time of 20 ms only 10 lateral pixels will be produced. This system can be useful for imaging of objects with very fast deviations in axial direction but with the small size of sample in the lateral direction. Therefore, additional methods are needed to increase data acquisition speed, sample scanning size and signal to noise ratio of the optical correlation-domain imaging.
- Another version of this invention utilizes the principal that when a light beam is diffracted by a moving diffraction grating ( DG ), the frequency of the diffracted light has a Doppler shift. Consider a diffraction grating DG moving in the direction of the grating dispersion ( x-axes ) with constant speed v, as can be seen in FIG. 10, the projections of the speed vector V on the direction of the reference ( signal ) beam are Vr,s=±v sinα, where ±α is the angle between the reference (signal ) beams and the normal to grating DG. The Doppler frequency shift (DFS) between diffracted reference and signal beams is
- ΔfD=2v f0sinα/c=2v sinα/λo=2v/p, (9)
- where p is the space between DG grooves and of, and λo are light frequency and wavelength, respectively.
- Eq. (9) shows that DFS does not depend upon the wavelength of the broadband source. This allows using a very narrow bandpass filter in a demodulator to increase SNR. This approach differs form other approaches wherein ΔfD depends on λ. For example, if v=30 mm/s and p=0.001 mm, then ΔfD=230/0.001=60 Khz. The output interference signal will be temporally modulated with a frequency equal of ΔfD.
- A system illustrating a moving grating arrangement and identified by reference numeral51 is shown in FIG. 11. System 51 includes a
laser light source 53, a first beamsplitter BSI, a second beamsplitter BS2, a grating DG, a reference mirror M5 a translation 55 for moving grating DG, a focusinglens 01, a collection lens L1, amultichannel diode array 57, ademodulator 59 and a computer 61. System 51 differs fromsystem 31 mainly in that the grating is movable and that the detector is a multichannel diode array and a demodulator. As can be seen, the optical signal from grating DG (i.e. the diffracted light) is directed to multichannel linear array (L.A.)detector 57. The optical signal is detected by demodulating the multichanneldiode array detector 57 output at the Doppler shift frequency (DSF). The output signal Wf(T) is given by: - Wf(T)˜P sj|γ(T−Tj)|, (10)
- where Psj, is amplitude reflectivity (square-root of the intensity reflectivity) of j-th boundary inside the sample, |γ(T−Tj)| is the degree of coherence. The summation in Eq.4 shows that each signal reflection produces a contribution to interference pattern proportional to the reflectivity Psj. The signal coming from the reflecting layers spread inside the object with different time delays produces a contribution to the interference pattern proportional to the layer reflectivity Psj. The full width at half maximum (FWHM) of each reflectivity peak will be equal to the amplitude correlation time , (FWHM of the degree of coherence |Ξ(T−Tj)| determining the resolution of this method. The accuracy with which reflection-site location can be determined depends only on the resolution of the diode array. If Δf D=60 Khz than the processing time of the each diode array pitch AC signal is about 10/60×103≈0.1 ms. The processing of the AC signals are performed in parallel for all pitches. The time response of 0.1 ms for each axial scan and the scan repetition rates of 104 l.p./s can be reached. For frequency-modulated interferometry the signal to noise ratio (SN R) of 100 dB may be achieved. This method performs high-resolution cross-sectional imaging by illuminating tissue with low-coherence light and measuring the back scattered light as a function of grating-generated time delay or range at different transverse positions.
- In the system shown in FIG. 11, the sample S is mounted on a stage (not shown) which is movable by means (not shown) in the “X” and “Y” directions so as to provide 3D imaging.
- The system in FIG. 11 provides a noncontact, high-sensitivity, high-resolution technique for optical imaging. High scan speeds are especially relevant for medical and biological diagnostic applications. Histological architecture of eye and tissue is of special interest is the noninvasive measurement of anterior eye dimensions and tissue diagnosis. In addition to diagnostics in biological systems, high-speed grating-generated depth scan has numerous applications for noncontact diagnostics of precision mechanical and optical systems as well as for process control and monitoring in manufacturing.
- This technique for performing an optical histological map (high-resolution micrometer-scale cross-sectional optical imaging) of tissue architectural morphology, such as an artery internal structure or internal structure of a mucous without the need to excise tissue specimens, would have a powerful effect on the diagnosis and clinical management of changes in tissue.
- Intravascular ultrasound is an existing catheter-based technique for obtaining cross-sectional images of human vasculature. However, the technique of this invention has the capability to image vascular lesions with much higher resolution and may be clinically useful for performing high-resolution imaging of other organ system, such as the artery, skin or GYN, GI tract or bladder.
- Cross-sectional analysis of paint samples by conventional or confocal incident light microscopy is routinely implemented during the initial examination of paintings undergoing conservation to study the structure of materials used and to identify their components. The technique of this invention has a number of important benefits over usual microscopy not least the increase in image resolution that can be obtained and the ability to produce high-speed serial optical sections of narrow Z-depth with high signal to noise ratio of 100 dB which can then be rendered into 3-d image. A major advantage of the technique of this invention is that it provides a quick and comparatively inexpensive method for accurately determine the boundaries of layers in a painting and their thickness. This technique can be used to determine if any overpainting has taken place, possibly due to previous conservation and, at high magnifications, sensitivity, could be used to identify pigment particles. A diagram to illustrate the typical cross-sectional structure of an oil painting is shown in FIG. 12, where (A) is particulate dirt deposits, (B) is varnish layer; (C) paint layer (pigment particles in a drying oil medium); (D) ground layer (lead white in a drying oil medium); Canvas support (usually linen) impregnated with size (usually animal glue). The incident pulse is reflected by these layers. The time delay between reflected pulses and pulse intensity consist information about the layers depth and reflectivity. This information can be extracted using the interferometric system of this invention.
- Combining the properties of the grating-generated coherent depth scan, Doppler frequency modulated interference and the multichannel detector parallel registration the increasing of the data acquisition speed and spatial resolution are achieved.
- The DFS between diffracted reference and signal beams can be also obtained if the DG is shaken along its plane as shown by arrow B by a piezotransducer (PZT) so that grating displacement is more than the grating groove space (See FIG. 13). This technique can simplify the interferometer mechanical part
- According to another aspect of the invention the acquisition speed is increased by using a diffraction grating that is rotating at a constant angle speed ω. Increasing of the grating tangential speed Vt is achieved in
system 71 shown in FIG. 14. Insystem 71, grating DG is attached by an arm 73 (not shown) to the drive shaft 75 of a motor (not shown). If ω=8 103 rpm and radius of the circle is of 5 cm than Vt=ωr=2λ8×103 ×50/60=4×104 mm/s and DFS ΔfD=2ωr/p=2×4×104/10−3=80 MHz. The AC signal processing time of the each diode array pitch is about 10/8×107≈0.1 μs. The time response of 0.1 μs for each axial scan and scan repetition rates (SRR) of 100 l.p./s can be realized. - There are several ways to increase the data acquisition speed.
- One way to increase the data acquisition speed is to increase the SRR use several diffraction gratings disposed on the sides of a multisided cylindrical device (See FIG. 15). These grating are rotated around the longitudinal axis of the device and the signal beam is discretely scanning in the x (or y) direction so that position of each rotating grating is synchronized with a certain x (or y) position of the scanning system. About 30 gratings of the 1 cm length can be used for the circle radius of 5 cm. The SRR is 3×103 l.p./s.2). If the diffraction grating is carried on cylindrical surface CS rotating with constant angle speed the maximum of the SRR and the lateral resolution can be realized (See FIG. 16). The SRR is 1 Mhz for 0.1 μs axial scan time response. To increase the axial resolution, the interference image output is collected by the fiber linear array FLA (See FIG. 17). Each fiber output is connected with a certain diode array pitch. The size of the each L.A. diode pitch is of 1 mm. The diameter of the single-mode fiber is about 100 μm and the tenfold increasing of the axial resolution can be achieved.
- To simplify the multichannel photodetector LA and electronic detection system the diffraction grating and fiber linear array connected with the multichannel photodetector are mounted on a fast moving translator (see FIG. 18).
- When the central wavelength (μ) of the laser source is discretely tuned the groove space p must satisfy the relation p=λ/sinα, where ±α is the angle between reference (or signal) beams and normal to the diffraction grating. It can be performed using a composition of several co-plane diffraction gratings with different groove spacings (See FIG. 12). The vertical position of the composition grating is discretely changed by the Y translator to satisfy the relation (3).
- In another embodiment of the invention, (See
system 71 in FIG. 20) the light source one is an array of diode lasers LA, each emitting light at different wavelength λ, according to relation (2). The LA laser source is mounted on a holder, accommodating y (or x) translational stage. The position of one laser diode is synchronized with the position of one diffraction grating. The wavelength is selected for the maximum depth exposure typically from 600 to 1600 nm. - To simplify the electronic detection system and to use a single detector instead of a diode LA, a rotating diffraction grating DG with a vertical extension in the form of a reflecting mirror ME is used as shown in system73 in FIG. 21. The diffracted beams are reflected from a stationary spherical mirror SM which displaces these beams in the vertical direction and directs them back to the rotating reflection mirror ME. Beams reflected from rotating mirror ME are directed into a vertical slit VS. The slit plane is optically conjugated with the grating plane by the reflecting spherical mirror SM. Optical signal passing the slit is detected by demodulating the single detector output at the Doppler shift frequency between signal and reference beams produced by rotating grating RG.
- To simplify the mechanical system using a PZT shaking grating DG, the diffracted signal and reference beams are reflected from a small angle shaking reflection mirror SRM as shown in system75 in FIG. 22.
- To increase the SRR without additional diffraction gratings one can use a small angle shaking mechanism SASM for shaking the diffraction grating which is carried on a spherical (or cylindrical) reflection surface with the vertical extension by the reflecting mirror. The axes of a small angle shaking are passing through the center of the grating spherical (or cylindrical) reflection surface (see FIG. 23).
- To increase the data acquisition speed the interferometric system can be performed so that beams reflected from the shaking (or rotation) grating are directed to the shaking (or rotation) reflection mirror SRM placed at the axes of shaking (or rotation) of the grating and after mirror reflection are directed to a stationary fiber array connected with the multichannel photodetector (see system77 in FIG. 24).
- To obtain an image of the surface structure of the human internal organ, such as artery cross section, tissue section or mucous the signal and reference interferometer arms are fiber-coupled as shown in system79 in FIG. 25. Tissue reflectance is obtained axially by the grating-generated depth scan and digitizing the magnitude of the demodulated interference envelope. The input of the signal beam fiber is connected with a catheter and the fiber output is connected with a lens LEI which directs the signal beam to the grating at the diffraction angle α. The fiber output of the reference beam is connected with a lens LE2 which directs the reference beam to the grating at the diffraction angle −α. Fiber optics allow to improve the flexibility of the interferometer set up. The catheter is designed to scan the beam in a circumferential pattern to image cross sectionally through the vessel (or other biological structure) into which it is inserted. During image acquisition the catheter is inserted into the tissue structure being imaged (the artery or other internal tissue channel), and, as the drive motor (not shown) turns, the shaft of the catheter and the distal optics circumferentially scan the focused beam perpendicular to the axis of the catheter. An image is acquired as the beam angle of rotation is varied over some range (usually 360 deg). The speed of imaging depends on the speed of the rotation and the proposed interferometer acquisition speed.
- This interferometric system can be used for optical communications as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography (see system81 in FIG. 26). In the case of the time-domain optical data storage one must detect signal beams despite the presence of relatively strong readout beams in close temporal and spatial proximity. The presence of strong readout beams can be turned to an advantage by use proposed technique. Our approach eliminates the need to ensure overlap between tightly focused and angled excitation beams and the need for optical shutters to prevent detector saturation by intense excitation beams. Other advantages include the ability to minimize cross talk between adjacent spatial storage cells and the ability to amplify signals sufficiently to overcome noise levels of photodiode-based detection system. A pulse code signal is directed on the grating at the diffraction angle α and a coherent reference pulse is directed on grating at the diffraction angle −α. For time-display window of 20 ps and the pulse amplitude correlation time of 100 fs the pulse code has about 2 103 bit. The information reading speed is of 2 109 bits/s with 1 MHz repetition rates for 1 μs axial scan time response. The SNR is about 100 dB.
- Due to economic advantages, maturing technology, and high information capacity, single-mode fiber-optic transmission media will be embedded in future telecommunications networks. A desirable feature for these future optical networks would be the ability to process information directly in the optical domain for purposes of multiplexing, de multiplexing, filtering, amplification, and correlation. Optical signal processing would be advantageous because potentially it can be much faster than electrical signal processing and because it would obviate the need for photon-electron-photon conversion.
- Characterization of weak ultrashort intensities is essential for single-event detection for time-domain communications. Ultrafast time-domain data packets can be created by the filtering of mode-locked laser pulses. Efficient detection of ultrashort time-domain signals requires novel receiver systems. The proposed interferometer can be performed as a receiver of a pulse code signal, received from the optical communication system (OCS) (see system83 in FIG. 27). The pulse code signal is directed on the grating at the diffraction angle a and coherent reference pulse extracted from OCS is directed on grating at the diffraction angle −α.
- The development of sub-picosecond laser sources has largely precluded techniques for accurate and complete characterization of pulses coming from such lasers. Today the most commonly used measurement is the nonlinear autocorrelation. While this technique generally require high intensity pulses. The spectral phase of femtosecond pulse can be measured using a frequency domain correlator. This technique involves cross correlating different spectral slices of the original pulse with itself. The relative delay of the spectral components with respect to each other provides information about any chirp which may be present. The interferometer can be performed so that signal beam includes zero-dispersion stretcher with moving slit placed in the stretcher spectral plane to measure dependence of the output signal position on the slit position (see system85 in FIG. 28). These measurements allow a person to obtain the spectral phase of the input pulse increasing measurement sensitivity and acquisition speed.
- In system91 shown in FIG. 29 signal and reference beams are focused by the combination of the cylindrical lenses into the narrow line on the surfaces of a grating and the 2D CCD array. Position of this narrow line is changed on the CCD array, for example, in vertical direction by a rotating mirror so that each lateral position of the signal beam produces the vertical shifted narrow line image on the CCD array. Several depth-lateral digital images are recorded with different phase shifts. These images are digital processing to produce a 3D image.
- In system99 shown in FIG. 30, the signal to noise ratio is increased using an interferometric system wherein the signal and reference beams are focused into a diffraction grating. The optical output signal is detected by demodulating the single detector output at the Doppler shift frequency.
- In another embodiment of the invention (not shown) the interferometric system is constructed so that a linear source image on the surface of the sample can be rotated, for example, by 90 degrees. A PZT stretched fiber is inserted to produce phase modulation. Several depth-lateral digital images are recorded by a 2D imaging CCD array with different phase shifts. These images are digital processing to produce a 3D image of the internal structure of a sample.
- In another embodiment of the invention (not shown) two perpendicular linear sources illuminate a sample simultaneously. Two diffraction gratings with perpendicular orientations of the grooves are used to create simultaneously two images on two CCD arrays to produce signals for a 3D image processing of the internal structure of a sample.
- In another embodiment of the invention (not shown) two orthogonal gratings placed at same or different locations, one or two CCD arrays are used to produce images in x or y directions in combination with the axial z scans of the depth of a sample along the grating dispersion. The images produced by the CCD arrays are used to create a 3D image of a sample.
- In FIG. 31 there is shown another embodiment of the invention identified by reference numeral101. System 101 includes an SLD light source 102, a pair of beamsplitters 103 and 104, a three lens 105, and 106 and 107 a rotating diffraction grating 107, a stretcher, 108, a mirror 109, a detector 110, electronics 111 and a computer 112.
- A further embodiment of the invention is shown in FIG. 32 and a view of the diffraction grating in the system in FIG. 32 is shown in FIG. 33.
- In FIG. 34 there is shown another embodiment of the invention identified by reference numeral121. In this embodiment, a diffracted reference beam is combined with reflections from a sample.
- In system121 light from source 123 strikes a first beamsplitter BS1 where it is split into a transmitted part and a reflected part. The reflected part is reflected off reference mirror M5. Reflected light from mirror M5, which constitutes a reference beam, passes back through beamsplitter BS1 and strikes diffraction grating DG. The transmitted part of the light passing through beamsplitter BS1 passes through beamsplitter BS2 and is brought to focus by a
lens 01 onto sample S. Diffraction grating DG is angled relative to the reference beam so that one of said first or second or higher diffraction orders from the light strikes the diffraction grating from the reference beams, either positive or negative is normal to the diffraction grating DG. The diffracted order that is normal to diffraction grating DG, identified in the FIG. As the diffracted reference beam, is combined with reflections from sample S by a second beamsplitter BS2. The combined beam is brought to focus into detector DET by a lens L1. The output of detective DET is fed into a computer COMP. - In FIG. 35 there is shown another embodiment of the invention identified by reference numeral131. System 131 differs from sytstem 121 in that diffraction grating DG is angled relative to the reference beam such that the reference beam is normal to the diffraction grating DG and the diffracted reference beam (either the first, second or higher order, and either positive or negative) that is combined with reflections from the sample is not normal to diffraction grating DG.
- System131 shown in FIG. 36 differs from system 121 in that the reference beam is not normal to diffraction grating DG.
-
System 141 shown in FIG. 37 differs from system 131 in that the first beamsplitter BS1 and the reference mirror M5 are eliminated. Instead, beamsplitter BS2 is used to produce a reference beam which strikes diffraction grating DG to produce a diffracted beam which is combined with reflections from the sample beam and sample beam which strikes the sample. - Important features of this invention include the following:
- 1. The use of diffraction grating to time resolve reflected signals from material by interference with reference pulse in ± first (or higher) diffraction orders.
- 2. The use of a time resolved interference method to obtain the depth map information for reflected signals from layers and defects in scattering medium.
- 3. The use of a time resolved interference method for a depth scan to obtain a depth map of a scattering medium below its surface up to 3 mm from the reflections within that region.
- 4. The use of a time resolved interference method for depth analyses of a tissue, semiconductor structure, art work on biological objects within a few mm depth. For tissue analyses it can be used to detect histological changes in tissue and artery wall such as plaque, fat, atheroscleroses.
- 5. A single-shot correlation-domain interferometric system using a grating-generated coherent depth scan interferometer and a broad-band laser source. The positive and the negative first-order diffracted signal and reference beams propagate along the normal to the grating. The diffraction grating introduces a continuous optical delay between the reference pulses and pulses reflected by the sample in the direction of the grating dispersion (x axis). In this case, pulses reflected by the surfaces located inside the sample are split by the diffraction grating in x-direction so that interference maxima showing depthscan reflections are also split in x-direction that permits the simultaneous registration of reflections using a CCD array. Each reflective layer at depth zi will be obtain as a signal to map its location.
- 6. Producing a high
dynamic range 2D (depth- transversal coordinate) interference image with a high resolution the interferometric system wherein the reference interferometer arm comprises a reflection mirror movable to the two different positions with a path difference more than grating time-display window (Td<20 ps) and a variable neutral-density filter. PZT stretched fiber can be inserted to create the delay time more than Td. A signal arm comprises a convex cylindrical (spherical) lens or their combination, to create, for example, a linear source image on the surface of the sample, and registration system. Two images are obtained. A 2D imaging CCD array acquires two images sequentially with (signal) and without (reference) interference corresponding for two different positions of the reference mirror. These signal and reference images are computer subtracted to produce a 2D (depth-transversal coordinate) dark-field interference image. - 7. Increasing the system sensitivity and dynamic range of the interferometric system of this invention one has a reference mirror moving by a PZT transducer into two positions with the path difference equal to λ/2, where λ is the source central wavelength. The positions of the reference mirror are managed by a photodetector—PZT feedback loop to acquire two images one is background+signal and the other is background−signal corresponding for the two positions of the PZT. These two images are subtracted to produce a 2D (depth- transversal coordinate) dark-field interference image with double sensitivity. In this way the background is removed and signal is doubled. (Background+signal)−(background−signal)=2 signal.
- 8. Increasing the data acquisition speed and removing background the interferometric system is performed using a reference arm comprising a focusing lens, acousto-optical modulator (AOM), 90° reflection prism, two reflection mirrors placed against the prism reflection sides so that the beam deflected by the AOM and reflected by the one of the prism side and one of the mirrors is directed back to the diffraction grating at the diffraction angle −α. CCD frames with and without interference are subtracted sequentially one from another to produce a series of the 2D (depth- transversal coordinate) dark-field interference images.
- 9. To perform optical tomography and histology or catheter-endoscope tomography the single-shot interferometric system is performed so that signal beam is scanning for example by a rotating mirror to illuminate a sample at different transverse positions. These signals are used to produce serial optical sections of narrow Z-depth for each transverse position which can then be rendered into 3-d image.
- 10. To increase the data acquisition speed, spatial resolution and signal to noise ratio the interferometric system includes a diffraction grating is moving along its plane with constant speed producing a Doppler shift frequency between signal and reference beams. The optical signal is detected by demodulating a multichannel linear array (LA) detector output at the Doppler shift frequency. In another version the diffraction grating is along its plane using, for example, a piezotransducer (PZT) so that grating displacement is more than the grating groove space.
- 11. Rotating the diffraction grating with constant angle speed to increase the tangential speed, DFS and the acquisition speed. In another version several diffraction gratings are disposed on the sides of the multisided cylindrical unit. These grating are rotated around the axes passing through the center and signal beam is discretely scanning in x (or y) direction so that position of each rotating grating is synchronized with a certain x (or y) position of the scanning system.
- 12. The use of diffraction grating carried on a cylindrical surface rotating with constant angle speed to increase the acquisition speed of the x (or y ) scanning system and the lateral resolution.
- 13. To increase the axial resolution of the interferometer the interference image output is collected by a fiber linear array. Each fiber output is connected with a certain diode array pitch.
- 14. To simplify the multichannel photodetector LA and electronic detection system a diffraction grating and fiber linear array connected with a multichannel photodetector are placed against each other on a fast moving translator.
- 15. A diffraction grating comprising a composition of the several co-plane diffraction gratings with different spacing between grooves. When the central wavelength (λ) of the laser source is discretely tuned the position of the composition, the grating is discretely changed so that the groove space p satisfies the next relation p=λ/sinα(1), where ±α is the angle between reference (or signal) beams and normal to the diffraction grating.
- Also, laser source is a linear array of the laser sources of different wavelengths λ (400 to 600 nm). The laser source array is mounted on a holder, accommodating x (or y) translational stage allow to choose appropriate wavelength of the laser source.
- 16. To increase the sensitivity for the tissue imaging using short wavelength radiation at maximum tissue absorption wavelength the interferometric system uses laser sources adapted to emit at second harmonics.
- 17. The interferometric system as claimed in claims7 to 11 wherein a vertical extension of the diffraction grating has a reflecting mirror. The diffracted beams are reflected from a stationary spherical mirror which displaces these beams in the vertical direction and directs them back to a rotating reflection mirror, Beams reflected from the rotating mirror are directed into a vertical slit. The slit plane is optically conjugated with the grating plane by the reflecting spherical mirror. Optical signal passing the slit is detected by demodulating the single detector output at the Doppler shift frequency between signal and reference beams produced by the rotating grating. This technique allows using a simple detection system.
- 18. To increase the data acquisition speed the interferometric system, beams reflected from a shaking (or rotation) grating are directed to a shaking (or rotation) reflection mirror placed at the axes of shaking (or rotation) of the grating and after mirror reflection are directed to a stationary fiber array connected to a multichannel photodetector.
- 19. To simplify the electronic detection, the interferometric system in a PZT shaking DG signal and reference beams are reflected from a small angle shaking reflection mirror. Beams reflected from the shaking mirror are directed into a vertical slit. Optical signal passing the slit is detected by demodulating the single detector output at the Doppler shift frequency.
- 20. To increase the SRR without additional diffraction gratings the diffraction grating is formed on the spherical (or cylindrical) reflection surface with a vertical extension reflecting mirror which is shaken over a small angle. The axes of the small angle shaking is passing through the center of the grating spherical (or cylindrical) reflection surface.
- 21. To get image of the sub structure of the human internal organ, mucous or tissue, for example an artery, the signal and reference interferometer arms are fiber-coupled. The input of the signal beam fiber is connected for example with a catheter and the fiber output is connected with a lens which directs the signal beam to the grating at a diffraction angle a. The fiber output of the reference beam is connected with a lens which directs the reference beam to the grating at the diffraction angle −α.
- 22. Using interferometric system as a receiver of a pulse code signal, retrieved from an optical memory system, for example, hole-burning holography. The pulse code signal is directed on the grating at the diffraction angle a and coherent reference pulse is directed on grating at the diffraction angle −α.
- 23. Using the interferometric system as a receiver of a pulse code signal, received from optical communication system (OCS) The pulse code signal is directed on the grating at the angle diffraction a and coherent reference pulse extracted from OCS is directed on grating at the diffraction angle −α.
- 24. An interferometric system having a signal beam which includes a zero-dispersion stretcher with moving slit placed in the stretcher spectral plane to measure dependence of the output signal position on the slit position. These measurements allow obtaining the spectral phase of the input pulse.
Claims (53)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/772,340 US6437867B2 (en) | 1996-12-04 | 2001-01-29 | Performing selected optical measurements with optical coherence domain reflectometry |
US10/201,404 US6762839B2 (en) | 1996-12-04 | 2002-07-22 | System and method for performing selected optical measurements utilizing a position changeable aperture |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US3322096P | 1996-12-04 | 1996-12-04 | |
US4248997P | 1997-04-02 | 1997-04-02 | |
US08/984,879 US5943133A (en) | 1996-12-04 | 1997-12-04 | System and method for performing selected optical measurements on a sample using a diffraction grating |
US37884699A | 1999-08-23 | 1999-08-23 | |
US09/772,340 US6437867B2 (en) | 1996-12-04 | 2001-01-29 | Performing selected optical measurements with optical coherence domain reflectometry |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US37884699A Continuation | 1996-12-04 | 1999-08-23 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/201,404 Continuation US6762839B2 (en) | 1996-12-04 | 2002-07-22 | System and method for performing selected optical measurements utilizing a position changeable aperture |
Publications (2)
Publication Number | Publication Date |
---|---|
US20010046054A1 true US20010046054A1 (en) | 2001-11-29 |
US6437867B2 US6437867B2 (en) | 2002-08-20 |
Family
ID=27488100
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/772,340 Expired - Fee Related US6437867B2 (en) | 1996-12-04 | 2001-01-29 | Performing selected optical measurements with optical coherence domain reflectometry |
US10/201,404 Expired - Fee Related US6762839B2 (en) | 1996-12-04 | 2002-07-22 | System and method for performing selected optical measurements utilizing a position changeable aperture |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/201,404 Expired - Fee Related US6762839B2 (en) | 1996-12-04 | 2002-07-22 | System and method for performing selected optical measurements utilizing a position changeable aperture |
Country Status (1)
Country | Link |
---|---|
US (2) | US6437867B2 (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2003058163A1 (en) * | 2001-12-05 | 2003-07-17 | Semiconductor Technologies & Instruments, Inc. | System and method for inspection using white light intererometry |
US20060051093A1 (en) * | 2004-08-11 | 2006-03-09 | Massimo Manna | System and method for spectral loading an optical transmission system |
US20060054800A1 (en) * | 2004-09-13 | 2006-03-16 | Leica Microsystems Cms Gmbh | Method for investigating transport processes |
US20060103850A1 (en) * | 2004-11-12 | 2006-05-18 | Alphonse Gerard A | Single trace multi-channel low coherence interferometric sensor |
CN102628799A (en) * | 2012-04-25 | 2012-08-08 | 中国科学院上海光学精密机械研究所 | Method and system of time-domain optical coherence tomography without depth scan |
CN104145177A (en) * | 2012-02-29 | 2014-11-12 | 国立大学法人香川大学 | Spectral characteristics measurement device and method for measuring spectral characteristics |
US20190162660A1 (en) * | 2017-05-03 | 2019-05-30 | Lumetrics, Inc. | Apparatus and method for measurement of multilayer structures |
CN110824684A (en) * | 2019-10-28 | 2020-02-21 | 华中科技大学 | High-speed three-dimensional multi-modal imaging system and method |
US20200149876A1 (en) * | 2017-07-12 | 2020-05-14 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on metal substrates using optical systems |
US10942345B2 (en) | 2016-03-14 | 2021-03-09 | Olympus Corporation | Image acquisition method and image acquisition device |
US11215444B2 (en) | 2017-05-03 | 2022-01-04 | Lumentrics, Inc. | Apparatus and method for measurement of multilayer structures |
Families Citing this family (125)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4241038B2 (en) | 2000-10-30 | 2009-03-18 | ザ ジェネラル ホスピタル コーポレーション | Optical method and system for tissue analysis |
US9295391B1 (en) | 2000-11-10 | 2016-03-29 | The General Hospital Corporation | Spectrally encoded miniature endoscopic imaging probe |
US7865231B2 (en) * | 2001-05-01 | 2011-01-04 | The General Hospital Corporation | Method and apparatus for determination of atherosclerotic plaque type by measurement of tissue optical properties |
US7355716B2 (en) | 2002-01-24 | 2008-04-08 | The General Hospital Corporation | Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands |
US20050020914A1 (en) * | 2002-11-12 | 2005-01-27 | David Amundson | Coronary sinus access catheter with forward-imaging |
US8054468B2 (en) | 2003-01-24 | 2011-11-08 | The General Hospital Corporation | Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands |
WO2004088361A2 (en) | 2003-03-31 | 2004-10-14 | The General Hospital Corporation | Speckle reduction in optical coherence tomography by path length encoded angular compounding |
US7376455B2 (en) * | 2003-05-22 | 2008-05-20 | Scimed Life Systems, Inc. | Systems and methods for dynamic optical imaging |
KR101386971B1 (en) | 2003-06-06 | 2014-04-18 | 더 제너럴 하스피탈 코포레이션 | Process and apparatus for a wavelength tunning source |
WO2005032339A2 (en) * | 2003-09-29 | 2005-04-14 | Dvx, Llc | Vessel flow monitoring system and method |
US7733497B2 (en) | 2003-10-27 | 2010-06-08 | The General Hospital Corporation | Method and apparatus for performing optical imaging using frequency-domain interferometry |
US20050254059A1 (en) * | 2004-05-14 | 2005-11-17 | Alphonse Gerard A | Low coherence interferometric system for optical metrology |
US7327463B2 (en) | 2004-05-14 | 2008-02-05 | Medrikon Corporation | Low coherence interferometry utilizing magnitude |
US7242480B2 (en) * | 2004-05-14 | 2007-07-10 | Medeikon Corporation | Low coherence interferometry for detecting and characterizing plaques |
US7474408B2 (en) * | 2004-05-14 | 2009-01-06 | Medeikon Corporation | Low coherence interferometry utilizing phase |
US7190464B2 (en) * | 2004-05-14 | 2007-03-13 | Medeikon Corporation | Low coherence interferometry for detecting and characterizing plaques |
US7184148B2 (en) | 2004-05-14 | 2007-02-27 | Medeikon Corporation | Low coherence interferometry utilizing phase |
AU2004320269B2 (en) | 2004-05-29 | 2011-07-21 | The General Hospital Corporation | Process, system and software arrangement for a chromatic dispersion compensation using reflective layers in optical coherence tomography (OCT) imaging |
WO2006014392A1 (en) | 2004-07-02 | 2006-02-09 | The General Hospital Corporation | Endoscopic imaging probe comprising dual clad fibre |
US8081316B2 (en) | 2004-08-06 | 2011-12-20 | The General Hospital Corporation | Process, system and software arrangement for determining at least one location in a sample using an optical coherence tomography |
WO2006024014A2 (en) | 2004-08-24 | 2006-03-02 | The General Hospital Corporation | Process, system and software arrangement for measuring a mechanical strain and elastic properties of a sample |
US8208995B2 (en) | 2004-08-24 | 2012-06-26 | The General Hospital Corporation | Method and apparatus for imaging of vessel segments |
US20060054801A1 (en) * | 2004-08-25 | 2006-03-16 | Long-Song Cheng | Biochip scanning device |
US7365859B2 (en) | 2004-09-10 | 2008-04-29 | The General Hospital Corporation | System and method for optical coherence imaging |
EP2329759B1 (en) | 2004-09-29 | 2014-03-12 | The General Hospital Corporation | System and method for optical coherence imaging |
US7995210B2 (en) | 2004-11-24 | 2011-08-09 | The General Hospital Corporation | Devices and arrangements for performing coherence range imaging using a common path interferometer |
JP2008521516A (en) | 2004-11-29 | 2008-06-26 | ザ ジェネラル ホスピタル コーポレイション | Configuration, apparatus, endoscope, catheter, and method for performing optical image generation by simultaneously illuminating and detecting multiple points on a sample |
EP2325803A1 (en) | 2005-04-28 | 2011-05-25 | The General Hospital Corporation | Evaluating optical coherence tomography information for an anatomical structure |
EP1887926B1 (en) * | 2005-05-31 | 2014-07-30 | The General Hospital Corporation | System and method which use spectral encoding heterodyne interferometry techniques for imaging |
US9060689B2 (en) | 2005-06-01 | 2015-06-23 | The General Hospital Corporation | Apparatus, method and system for performing phase-resolved optical frequency domain imaging |
ES2354287T3 (en) | 2005-08-09 | 2011-03-11 | The General Hospital Corporation | APPARATUS AND METHOD FOR PERFORMING A DEMODULATION IN QUADRATURE BY POLARIZATION IN OPTICAL COHERENCE TOMOGRAPHY. |
CN101365375B (en) | 2005-09-29 | 2013-09-11 | 通用医疗公司 | Method and apparatus for optical imaging via spectral encoding |
US7889348B2 (en) | 2005-10-14 | 2011-02-15 | The General Hospital Corporation | Arrangements and methods for facilitating photoluminescence imaging |
US7397563B2 (en) * | 2005-11-08 | 2008-07-08 | Honeywell International Inc. | Pass-line insensitive sensor |
US7460233B2 (en) * | 2005-11-08 | 2008-12-02 | Honeywell International Inc. | Pass-line and tilt insensitive sensor |
EP1971848B1 (en) | 2006-01-10 | 2019-12-04 | The General Hospital Corporation | Systems and methods for generating data based on one or more spectrally-encoded endoscopy techniques |
PL1973466T3 (en) | 2006-01-19 | 2021-07-05 | The General Hospital Corporation | Ballon imaging catheter |
US8145018B2 (en) | 2006-01-19 | 2012-03-27 | The General Hospital Corporation | Apparatus for obtaining information for a structure using spectrally-encoded endoscopy techniques and methods for producing one or more optical arrangements |
JP5524487B2 (en) | 2006-02-01 | 2014-06-18 | ザ ジェネラル ホスピタル コーポレイション | A method and system for emitting electromagnetic radiation to at least a portion of a sample using a conformal laser treatment procedure. |
WO2007149603A2 (en) | 2006-02-01 | 2007-12-27 | The General Hospital Corporation | Apparatus for applying a plurality of electro-magnetic radiations to a sample |
JP5519152B2 (en) | 2006-02-08 | 2014-06-11 | ザ ジェネラル ホスピタル コーポレイション | Device for acquiring information about anatomical samples using optical microscopy |
EP1987318B1 (en) | 2006-02-24 | 2015-08-12 | The General Hospital Corporation | Methods and systems for performing angle-resolved fourier-domain optical coherence tomography |
EP2517616A3 (en) | 2006-05-10 | 2013-03-06 | The General Hospital Corporation | Processes, arrangements and systems for providing frequency domain imaging of a sample |
US7488930B2 (en) * | 2006-06-02 | 2009-02-10 | Medeikon Corporation | Multi-channel low coherence interferometer |
DE102006028238B3 (en) * | 2006-06-20 | 2007-07-19 | Benecke-Kaliko Ag | Three dimensionally structured original surface e.g. grained surface, reflection characteristics analysis and specification method, involves storing reflection value in data record that is provided to processing or verification system |
CN101589301B (en) | 2006-08-25 | 2012-11-07 | 通用医疗公司 | Apparatus and methods for enhancing optical coherence tomography imaging using volumetric filtering techniques |
WO2008049118A2 (en) | 2006-10-19 | 2008-04-24 | The General Hospital Corporation | Apparatus and method for obtaining and providing imaging information associated with at least one portion of a sample and effecting such portion(s) |
US7949019B2 (en) | 2007-01-19 | 2011-05-24 | The General Hospital | Wavelength tuning source based on a rotatable reflector |
EP2602651A3 (en) | 2007-03-23 | 2014-08-27 | The General Hospital Corporation | Methods, arrangements and apparatus for utilizing a wavelength-swept laser using angular scanning and dispersion procedures |
US10534129B2 (en) | 2007-03-30 | 2020-01-14 | The General Hospital Corporation | System and method providing intracoronary laser speckle imaging for the detection of vulnerable plaque |
WO2008131082A1 (en) | 2007-04-17 | 2008-10-30 | The General Hospital Corporation | Apparatus and methods for measuring vibrations using spectrally-encoded endoscopy techniques |
JP5917803B2 (en) | 2007-07-31 | 2016-05-18 | ザ ジェネラル ホスピタル コーポレイション | System and method for emitting a beam scanning pattern for fast Doppler optical frequency domain imaging |
EP2826436B1 (en) | 2007-09-06 | 2018-03-28 | Alcon LenSx, Inc. | Precise targeting of surgical photodisruption |
JP2009083448A (en) * | 2007-10-03 | 2009-04-23 | Seiko Instruments Inc | Printer and issuing apparatus |
WO2009059034A1 (en) | 2007-10-30 | 2009-05-07 | The General Hospital Corporation | System and method for cladding mode detection |
US7898656B2 (en) | 2008-04-30 | 2011-03-01 | The General Hospital Corporation | Apparatus and method for cross axis parallel spectroscopy |
EP2274572A4 (en) | 2008-05-07 | 2013-08-28 | Gen Hospital Corp | System, method and computer-accessible medium for tracking vessel motion during three-dimensional coronary artery microscopy |
WO2009155536A2 (en) | 2008-06-20 | 2009-12-23 | The General Hospital Corporation | Fused fiber optic coupler arrangement and method for use thereof |
US8673163B2 (en) | 2008-06-27 | 2014-03-18 | Apple Inc. | Method for fabricating thin sheets of glass |
US7810355B2 (en) | 2008-06-30 | 2010-10-12 | Apple Inc. | Full perimeter chemical strengthening of substrates |
WO2010009136A2 (en) | 2008-07-14 | 2010-01-21 | The General Hospital Corporation | Apparatus and methods for color endoscopy |
US8018815B2 (en) * | 2008-08-15 | 2011-09-13 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Micro-Fresnel zone plate optical devices using densely accumulated ray points |
US8059273B2 (en) * | 2008-08-15 | 2011-11-15 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Micro spectrometer for parallel light and method of use |
US8094306B2 (en) * | 2008-08-15 | 2012-01-10 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Micro ring grating spectrometer with adjustable aperture |
US8174695B2 (en) * | 2008-08-15 | 2012-05-08 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Arrayed micro-ring spectrometer system and method of use |
JP5731394B2 (en) | 2008-12-10 | 2015-06-10 | ザ ジェネラル ホスピタル コーポレイション | System, apparatus and method for extending imaging depth range of optical coherence tomography through optical subsampling |
US9615748B2 (en) | 2009-01-20 | 2017-04-11 | The General Hospital Corporation | Endoscopic biopsy apparatus, system and method |
WO2010085775A2 (en) | 2009-01-26 | 2010-07-29 | The General Hospital Corporation | System, method and computer-accessible medium for providing wide-field superresolution microscopy |
CN102308444B (en) | 2009-02-04 | 2014-06-18 | 通用医疗公司 | Apparatus and method for utilization of a high-speed optical wavelength tuning source |
WO2010101961A2 (en) | 2009-03-02 | 2010-09-10 | Apple Inc. | Techniques for strengthening glass covers for portable electronic devices |
BR112012001042A2 (en) | 2009-07-14 | 2016-11-22 | Gen Hospital Corp | fluid flow measurement equipment and method within anatomical structure. |
US8294989B2 (en) * | 2009-07-30 | 2012-10-23 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Apparatus and method for creating a photonic densely-accumulated ray-point |
US9492322B2 (en) * | 2009-11-16 | 2016-11-15 | Alcon Lensx, Inc. | Imaging surgical target tissue by nonlinear scanning |
US9778685B2 (en) | 2011-05-04 | 2017-10-03 | Apple Inc. | Housing for portable electronic device with reduced border region |
US8265364B2 (en) | 2010-02-05 | 2012-09-11 | Alcon Lensx, Inc. | Gradient search integrated with local imaging in laser surgical systems |
US8414564B2 (en) | 2010-02-18 | 2013-04-09 | Alcon Lensx, Inc. | Optical coherence tomographic system for ophthalmic surgery |
ES2831223T3 (en) | 2010-03-05 | 2021-06-07 | Massachusetts Gen Hospital | Apparatus for providing electromagnetic radiation to a sample |
US9069130B2 (en) | 2010-05-03 | 2015-06-30 | The General Hospital Corporation | Apparatus, method and system for generating optical radiation from biological gain media |
US9557154B2 (en) | 2010-05-25 | 2017-01-31 | The General Hospital Corporation | Systems, devices, methods, apparatus and computer-accessible media for providing optical imaging of structures and compositions |
US9795301B2 (en) | 2010-05-25 | 2017-10-24 | The General Hospital Corporation | Apparatus, systems, methods and computer-accessible medium for spectral analysis of optical coherence tomography images |
EP2575591A4 (en) | 2010-06-03 | 2017-09-13 | The General Hospital Corporation | Apparatus and method for devices for imaging structures in or at one or more luminal organs |
US9213451B2 (en) | 2010-06-04 | 2015-12-15 | Apple Inc. | Thin glass for touch panel sensors and methods therefor |
US10189743B2 (en) | 2010-08-18 | 2019-01-29 | Apple Inc. | Enhanced strengthening of glass |
US8873028B2 (en) * | 2010-08-26 | 2014-10-28 | Apple Inc. | Non-destructive stress profile determination in chemically tempered glass |
US9532708B2 (en) | 2010-09-17 | 2017-01-03 | Alcon Lensx, Inc. | Electronically controlled fixation light for ophthalmic imaging systems |
US8824140B2 (en) | 2010-09-17 | 2014-09-02 | Apple Inc. | Glass enclosure |
US8950215B2 (en) | 2010-10-06 | 2015-02-10 | Apple Inc. | Non-contact polishing techniques for reducing roughness on glass surfaces |
US8049886B1 (en) * | 2010-10-14 | 2011-11-01 | Alcon Lensx, Inc. | Spectrometer with adjustable-deflector-controlled alignment for optical coherence tomography |
US9510758B2 (en) | 2010-10-27 | 2016-12-06 | The General Hospital Corporation | Apparatus, systems and methods for measuring blood pressure within at least one vessel |
US9725359B2 (en) | 2011-03-16 | 2017-08-08 | Apple Inc. | Electronic device having selectively strengthened glass |
US8459794B2 (en) | 2011-05-02 | 2013-06-11 | Alcon Lensx, Inc. | Image-processor-controlled misalignment-reduction for ophthalmic systems |
US9128666B2 (en) | 2011-05-04 | 2015-09-08 | Apple Inc. | Housing for portable electronic device with reduced border region |
US9622913B2 (en) | 2011-05-18 | 2017-04-18 | Alcon Lensx, Inc. | Imaging-controlled laser surgical system |
WO2013013049A1 (en) | 2011-07-19 | 2013-01-24 | The General Hospital Corporation | Systems, methods, apparatus and computer-accessible-medium for providing polarization-mode dispersion compensation in optical coherence tomography |
US10241028B2 (en) | 2011-08-25 | 2019-03-26 | The General Hospital Corporation | Methods, systems, arrangements and computer-accessible medium for providing micro-optical coherence tomography procedures |
US8398238B1 (en) | 2011-08-26 | 2013-03-19 | Alcon Lensx, Inc. | Imaging-based guidance system for ophthalmic docking using a location-orientation analysis |
US9944554B2 (en) | 2011-09-15 | 2018-04-17 | Apple Inc. | Perforated mother sheet for partial edge chemical strengthening and method therefor |
US9516149B2 (en) | 2011-09-29 | 2016-12-06 | Apple Inc. | Multi-layer transparent structures for electronic device housings |
EP2769491A4 (en) | 2011-10-18 | 2015-07-22 | Gen Hospital Corp | Apparatus and methods for producing and/or providing recirculating optical delay(s) |
US10144669B2 (en) | 2011-11-21 | 2018-12-04 | Apple Inc. | Self-optimizing chemical strengthening bath for glass |
US9023016B2 (en) | 2011-12-19 | 2015-05-05 | Alcon Lensx, Inc. | Image processor for intra-surgical optical coherence tomographic imaging of laser cataract procedures |
US9066784B2 (en) | 2011-12-19 | 2015-06-30 | Alcon Lensx, Inc. | Intra-surgical optical coherence tomographic imaging of cataract procedures |
US10133156B2 (en) | 2012-01-10 | 2018-11-20 | Apple Inc. | Fused opaque and clear glass for camera or display window |
US8773848B2 (en) | 2012-01-25 | 2014-07-08 | Apple Inc. | Fused glass device housings |
WO2013148306A1 (en) | 2012-03-30 | 2013-10-03 | The General Hospital Corporation | Imaging system, method and distal attachment for multidirectional field of view endoscopy |
WO2013177154A1 (en) | 2012-05-21 | 2013-11-28 | The General Hospital Corporation | Apparatus, device and method for capsule microscopy |
JP6227652B2 (en) | 2012-08-22 | 2017-11-08 | ザ ジェネラル ホスピタル コーポレイション | System, method, and computer-accessible medium for fabricating a miniature endoscope using soft lithography |
US9946302B2 (en) | 2012-09-19 | 2018-04-17 | Apple Inc. | Exposed glass article with inner recessed area for portable electronic device housing |
JP6560126B2 (en) | 2013-01-28 | 2019-08-14 | ザ ジェネラル ホスピタル コーポレイション | Apparatus and method for providing diffusion spectroscopy superimposed on optical frequency domain imaging |
WO2014120791A1 (en) | 2013-01-29 | 2014-08-07 | The General Hospital Corporation | Apparatus, systems and methods for providing information regarding the aortic valve |
US11179028B2 (en) | 2013-02-01 | 2021-11-23 | The General Hospital Corporation | Objective lens arrangement for confocal endomicroscopy |
JP6378311B2 (en) | 2013-03-15 | 2018-08-22 | ザ ジェネラル ホスピタル コーポレイション | Methods and systems for characterizing objects |
WO2014186353A1 (en) | 2013-05-13 | 2014-11-20 | The General Hospital Corporation | Detecting self-interefering fluorescence phase and amplitude |
US9459661B2 (en) | 2013-06-19 | 2016-10-04 | Apple Inc. | Camouflaged openings in electronic device housings |
EP3021735A4 (en) | 2013-07-19 | 2017-04-19 | The General Hospital Corporation | Determining eye motion by imaging retina. with feedback |
WO2015009932A1 (en) | 2013-07-19 | 2015-01-22 | The General Hospital Corporation | Imaging apparatus and method which utilizes multidirectional field of view endoscopy |
EP3025173B1 (en) | 2013-07-26 | 2021-07-07 | The General Hospital Corporation | Apparatus with a laser arrangement utilizing optical dispersion for applications in fourier-domain optical coherence tomography |
US9733460B2 (en) | 2014-01-08 | 2017-08-15 | The General Hospital Corporation | Method and apparatus for microscopic imaging |
WO2015116986A2 (en) | 2014-01-31 | 2015-08-06 | The General Hospital Corporation | System and method for facilitating manual and/or automatic volumetric imaging with real-time tension or force feedback using a tethered imaging device |
US9886062B2 (en) | 2014-02-28 | 2018-02-06 | Apple Inc. | Exposed glass article with enhanced stiffness for portable electronic device housing |
WO2015153982A1 (en) | 2014-04-04 | 2015-10-08 | The General Hospital Corporation | Apparatus and method for controlling propagation and/or transmission of electromagnetic radiation in flexible waveguide(s) |
WO2016015052A1 (en) | 2014-07-25 | 2016-01-28 | The General Hospital Corporation | Apparatus, devices and methods for in vivo imaging and diagnosis |
WO2017223149A1 (en) | 2016-06-21 | 2017-12-28 | The Regents Of The University Of California | Single-shot network analyzer (sina) |
JP6887350B2 (en) * | 2017-09-06 | 2021-06-16 | 株式会社日立製作所 | Optical image measuring device |
KR102632562B1 (en) | 2018-08-22 | 2024-02-02 | 삼성전자주식회사 | Inspecting apparatus and method based on SI(Structured Illumination), and method for fabricating semiconductor device comprising the inspecting method |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3614235A (en) | 1969-07-28 | 1971-10-19 | Charles R Munnerlyn | Diffraction grating interferometer |
DE2627609A1 (en) | 1976-06-19 | 1977-12-29 | Ibm Deutschland | INTERFEROMETRIC PROCEDURE |
WO1992019930A1 (en) | 1991-04-29 | 1992-11-12 | Massachusetts Institute Of Technology | Method and apparatus for optical imaging and measurement |
CH693968A5 (en) | 1993-04-21 | 2004-05-14 | Fraunhofer Ges Forschung | Method and apparatus for the Topographiepruefung of surfaces. |
ATE155238T1 (en) | 1994-02-26 | 1997-07-15 | Heidenhain Gmbh Dr Johannes | INTERFEROMETER |
WO1997022274A1 (en) | 1995-12-15 | 1997-06-26 | Etablissements Sarran S.A. | Device for attaching a strap to a watch casing |
JP4020434B2 (en) | 1996-12-04 | 2007-12-12 | ザ・リサーチ・ファンデーション・オブ・シティ・ユニバーシティ・オブ・ニューヨーク | Apparatus and method for selective optical measurement |
-
2001
- 2001-01-29 US US09/772,340 patent/US6437867B2/en not_active Expired - Fee Related
-
2002
- 2002-07-22 US US10/201,404 patent/US6762839B2/en not_active Expired - Fee Related
Cited By (24)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040090634A1 (en) * | 2001-12-05 | 2004-05-13 | Sanjeev Mathur | System and method for inspection using white light intererometry |
WO2003058163A1 (en) * | 2001-12-05 | 2003-07-17 | Semiconductor Technologies & Instruments, Inc. | System and method for inspection using white light intererometry |
US7158235B2 (en) | 2001-12-05 | 2007-01-02 | Rudolph Technologies, Inc. | System and method for inspection using white light interferometry |
US20060051093A1 (en) * | 2004-08-11 | 2006-03-09 | Massimo Manna | System and method for spectral loading an optical transmission system |
US8064770B2 (en) * | 2004-08-11 | 2011-11-22 | Tyco Electronics Subsea Communications Llc | System and method for spectral loading an optical transmission system |
US7482600B2 (en) * | 2004-09-13 | 2009-01-27 | Leica Microsystems Cms Gmbh | Method for investigating transport processes |
US20060054800A1 (en) * | 2004-09-13 | 2006-03-16 | Leica Microsystems Cms Gmbh | Method for investigating transport processes |
US7417740B2 (en) | 2004-11-12 | 2008-08-26 | Medeikon Corporation | Single trace multi-channel low coherence interferometric sensor |
US20060103850A1 (en) * | 2004-11-12 | 2006-05-18 | Alphonse Gerard A | Single trace multi-channel low coherence interferometric sensor |
CN104145177A (en) * | 2012-02-29 | 2014-11-12 | 国立大学法人香川大学 | Spectral characteristics measurement device and method for measuring spectral characteristics |
US9474476B2 (en) | 2012-02-29 | 2016-10-25 | National University Corporation Kagawa University | Spectral characteristics measurement device and spectral characteristics measurement method |
CN102628799A (en) * | 2012-04-25 | 2012-08-08 | 中国科学院上海光学精密机械研究所 | Method and system of time-domain optical coherence tomography without depth scan |
US10942345B2 (en) | 2016-03-14 | 2021-03-09 | Olympus Corporation | Image acquisition method and image acquisition device |
US20190162660A1 (en) * | 2017-05-03 | 2019-05-30 | Lumetrics, Inc. | Apparatus and method for measurement of multilayer structures |
US10761021B2 (en) * | 2017-05-03 | 2020-09-01 | Lumetrics, Inc. | Apparatus and method for measurement of multilayer structures |
US11215444B2 (en) | 2017-05-03 | 2022-01-04 | Lumentrics, Inc. | Apparatus and method for measurement of multilayer structures |
US20200149876A1 (en) * | 2017-07-12 | 2020-05-14 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on metal substrates using optical systems |
US10928185B2 (en) * | 2017-07-12 | 2021-02-23 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on metal substrates using optical systems |
US11143500B2 (en) * | 2017-07-12 | 2021-10-12 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of automobile paints and transparent coatings |
US11143501B2 (en) | 2017-07-12 | 2021-10-12 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on metal substrates of appliances |
US11226192B2 (en) | 2017-07-12 | 2022-01-18 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on substrates of aerospace components |
US20220099433A1 (en) * | 2017-07-12 | 2022-03-31 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on substrates of aerospace components |
US11680791B2 (en) * | 2017-07-12 | 2023-06-20 | Sensory Analytics, Llc | Methods and systems for real-time, in-process measurement of coatings on substrates of aerospace components |
CN110824684A (en) * | 2019-10-28 | 2020-02-21 | 华中科技大学 | High-speed three-dimensional multi-modal imaging system and method |
Also Published As
Publication number | Publication date |
---|---|
US20030090674A1 (en) | 2003-05-15 |
US6437867B2 (en) | 2002-08-20 |
US6762839B2 (en) | 2004-07-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6437867B2 (en) | Performing selected optical measurements with optical coherence domain reflectometry | |
US5943133A (en) | System and method for performing selected optical measurements on a sample using a diffraction grating | |
WO1998025105A9 (en) | A system and method for performing selected optical measurements | |
US7697145B2 (en) | System for fourier domain optical coherence tomography | |
EP1971848B1 (en) | Systems and methods for generating data based on one or more spectrally-encoded endoscopy techniques | |
US7061622B2 (en) | Aspects of basic OCT engine technologies for high speed optical coherence tomography and light source and other improvements in optical coherence tomography | |
US6853457B2 (en) | Optical amplification in coherence reflectometry | |
US6900943B2 (en) | Optical amplification in coherent optical frequency modulated continuous wave reflectometry | |
US8081316B2 (en) | Process, system and software arrangement for determining at least one location in a sample using an optical coherence tomography | |
EP0581871B1 (en) | Apparatus for optical imaging and measurement | |
US7911621B2 (en) | Apparatus and method for controlling ranging depth in optical frequency domain imaging | |
JP4344829B2 (en) | Polarized light receiving image measuring device | |
EP1611411A2 (en) | Method and apparatus for imaging internal structures of transparent and translucent materials | |
WO2001061318A1 (en) | Optical interference tomographic image observing apparatus | |
US20200359903A1 (en) | Coherence gated photoacoustic remote sensing (cg-pars) | |
Hauger et al. | High-speed low-coherence interferometer for optical coherence tomography | |
RU2184347C2 (en) | Process generating images of internal structure of objects | |
Zeylikovich et al. | Three-exposure interferometric histological image reconstruction of biological tissue | |
Laubscher | Innovative experimental concepts for optical coherence tomography | |
Yoshimura et al. | Optical coherence tomography in scattering media using a continuous-wave tunable laser diode | |
Li et al. | Optical coherence tomography endoscopic imaging system using mini-ultrasonic motor | |
Chen et al. | Spectral-domain optical coherence tomography for endoscopic imaging | |
Jonusauskas et al. | Development of Tomography Using Femtosecond Infrared Laser: Imaging of Biological Tissues | |
Ma et al. | Three-phase shifting method for full range spectral optical coherence tomography |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: RESEARCH FOUNDATION OF THE CITY UNIVERSITY OF NEW Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ZEYLIKOVICH, IOSIF;ALFANO, ROBERT R.;REEL/FRAME:012651/0253;SIGNING DATES FROM 20010713 TO 20020207 |
|
FEPP | Fee payment procedure |
Free format text: PAT HOLDER CLAIMS SMALL ENTITY STATUS, ENTITY STATUS SET TO SMALL (ORIGINAL EVENT CODE: LTOS); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: PAT HOLDER NO LONGER CLAIMS SMALL ENTITY STATUS, ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: STOL); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
REFU | Refund |
Free format text: REFUND - PAYMENT OF MAINTENANCE FEE, 8TH YR, SMALL ENTITY (ORIGINAL EVENT CODE: R2552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
REMI | Maintenance fee reminder mailed | ||
LAPS | Lapse for failure to pay maintenance fees | ||
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20140820 |