WO2008150050A1

WO2008150050A1 - High speed optical monitoring system using a rotatable mirror

Info

Publication number: WO2008150050A1
Application number: PCT/KR2007/006138
Authority: WO
Inventors: Dong-Youn Shin; Kyung Hyun Hwang
Original assignee: Korea Institute Of Machinery & Materials
Priority date: 2007-06-07
Filing date: 2007-11-30
Publication date: 2008-12-11
Also published as: TW200849147A

Abstract

The present invention provides a high speed optical monitoring system for monitoring at least one subject. The system includes at least one subject source for generating the subject; a subject source support for aligning and supporting the subject source so as to position the subject in an identical focal space plane; an image acquisition unit having an imaging device for monitoring and imaging the subject at an aligned position; a mirror mounted between the subject and the image acquisition unit such that a rotational angle of the mirror can be changed; a focus compensation lens arranged between the subject and the mirror; an image processing unit for processing an image acquired by the image acquisition unit into digital data; a lighting unit for illuminating the subject; and a system control unit for controlling the lighting unit and driving of the subject source, the image acquisition unit and the mirror. According to the present invention thus constructed, a plurality of subjects can be monitored in a high speed manner, and at the same time, a clear monitored image can be obtained from the subjects.

Description

HIGH SPEED OPTICAL MONITORING SYSTEM USING A

ROTATABLE MIRROR

Technical Field

[1] The present invention relates to a high speed optical monitoring system, and more particularly, to a high speed optical monitoring system capable of clearly monitoring at least one subject arranged on an identical focal space plane in a high speed manner.

[2]

Background Art

[3] A conventional subject monitoring apparatus 101 for monitoring a plurality of subjects is constructed such that a subject monitoring camera 120 is mounted on at least one moving stage 130 and moved in an X-direction and/or a Y-direction to monitor sequentially monitor subjects 110 existing in an identical focal space plane F.

[4] Alternatively, a subject source 111 generating the subjects 110 is moved together with a subject source support 112 by at least one moving stage 131 in an X-direction and/or in a Y-direction in a state where the camera 120 is fixed, so that the camera 120 can sequentially and individually monitor the subjects 110.

[5] Meanwhile, the camera 120 and the subjects 110 are arranged such that the subjects

110 can be sequentially monitored by the camera 120 while both the moving stage 130 for the camera 120 and the moving stage 131 for the subject source 111 and the subject source support 112 are mutually moved.

[6] In the conventional subject monitoring apparatus as described above, however, since the subjects are monitored while the camera and/or the subjects are moved by the moving stages , monitoring time is delayed by required time durations depending on the moving distances of the moving stages, resulting in a problem of difficulty in monitoring the subjects in a high speed manner.

[7] More specifically, since the moving stages are repetitively reciprocated in the X direction and/or in the Y direction so as to periodically monitor a plurality of subjects, there is a problem in that, due to inertial forces of the moving stage and an object to be moved, i.e., the camera or the subjects, it is actually difficult to reciprocate the moving stages and the object to be moved in a high speed manner without vibration. Accordingly, there are problems in that images of the subjects monitored by the camera are distorted and the subjects cannot be monitored in a high speed manner.

[8]

Disclosure of Invention Technical Problem [9] Accordingly, an object of the present invention is to provide a high speed optical monitoring system capable of monitoring at least one subject in a high speed manner and simultaneously obtaining a clear monitored image from the subject.

[10]

Technical Solution

[11] According to an aspect of the present invention for achieving the object, there is provided a high speed optical monitoring system for monitoring at least one subject, comprising: at least one subject source for generating the subject; a subject source support for aligning and supporting the subject source so as to position the subject in an identical focal space plane; an image acquisition unit having an imaging device for monitoring and imaging the subject at an aligned position; a mirror mounted between the subject and the image acquisition unit such that a rotational angle of the mirror can be changed; a focus compensation lens arranged between the subject and the mirror; an image processing unit for processing an image acquired by the image acquisition unit into digital data; a lighting unit for illuminating the subject; and a system control unit for controlling the lighting unit and driving of the subject source, the image acquisition unit and the mirror.

[12] The at least one subject may comprise a plurality of subjects, and the subjects may be stationary or moved, or may be generated in a periodic or quasi-periodic manner and moved dynamically.

[13] The high speed optical monitoring system may further comprise a subject source alignment unit coupled to the subject source support so as to move the subject source along X/Y/Z axes and to tilt or rotate the subject source about the X/Y/Z axes.

[14] The image acquisition unit may be a camera having a CCD or CMOS imaging device.

[15] The mirror may comprise a mirror body composed of a planar mirror having at least one single mirror surface; and a mirror driving unit for rotating the mirror body through a certain rotational angle.

[16] The mirror may comprise a mirror body composed of a polygon mirror having a plurality of mirror surfaces; and a mirror driving unit for rotating the mirror body through a certain rotational angle.

[17] The focus compensation lens may be provided as a single F-theta aspheric lens, a plurality of aspheric lenses, or a combination of spherical lens/aspheric lens.

[18] The subject may be moved and the lighting unit may employ an impulse-type light emitting diode or laser diode associated with the movement of the subject that is moved.

[19] The high speed optical monitoring system may further comprise a light quantity variation compensation unit provided on an optical path between the subject and the image acquisition unit so as to compensate a light quantity variation of the lighting unit.

[20] The lighting unit may be provided behind the subject or in the image acquisition unit to illuminate the subject. If the lighting unit is provided in the image acquisition unit, a reflecting plate may be provided behind the subject.

[21] The lighting unit may comprise an air cooling type or water cooling type cooling device for blocking heat generated from a lighting source.

[22] The cooling device may comprise at least one of an IR (infrared) filter and a dichroic optical filter.

[23] The cooling device may be a Peltier element.

[24] At least one optical filter of an infrared blocking filter, a polarization filter, a color filter and a band pass filter may be provided on an optical path between the subject and the image acquisition unit.

[25] The high speed optical monitoring system may further comprise a reference sample arranged in the identical focal space plane so as to check and calibrate optical alignment relations between the subject and the image acquisition unit and between the mirror body and the focus compensation lens.

[26] The high speed optical monitoring system may further comprise a reference sample support arranged in the identical focal space plane so as to support the reference sample, wherein the reference sample support may be detachably coupled in the identical focal space plane or may be installed to be movable between a position at which the reference sample support is arranged in the identical focal space plane and another position out of the identical focal space plane.

[27] The reference sample support may be positioned manually or automatically in the identical focal space plane.

[28] The reference sample may have a pattern corresponding to the subject and formed on a substrate made of a transparent, translucent or opaque material.

[29] The pattern of the reference sample may be acquired as an image by the image acquisition unit, so that correlation between the image and the size of the pattern can be used to calibrate the optical alignment relations between the subject and the image acquisition unit and between the mirror and the focus compensation lens as well as to calibrate the image processing performance.

[30] The mirror driving unit may transmit an electrical detection signal for the rotational angle of the mirror body to the system control unit, and the system control unit may receive the electrical detection signal for the rotation angle of the mirror body and control driving of the mirror driving unit so as to control the rotational angle of the mirror body. [31] The high speed optical monitoring system may further comprise a beam radiating unit for radiating light onto the mirror body and a mirror-reflected light detection sensor for sensing the light reflected on the mirror body, wherein the system control unit may control driving of the mirror driving unit based on a sensed value transmitted from the mirror-reflected light detection sensor so as to control the rotational angle of the mirror body.

[32] The system control unit may acquire the quantity of light and a light quantity variation of the lighting unit depending on the frequency, pulsed time, driving voltage or current of the lighting unit, or the quantities of light of lighting sources of the lighting unit and light quantity variations between the lighting sources by the image acquisition unit, and then measure the quantity or quantities of light and the light quantity variation or variations in a software manner to control the quantity of light of the lighting unit or the lighting sources and the light quantity variation between the lighting sources of the lighting unit or compensate an image acquired by the image acquisition unit but distorted by due to the quantity of light and the light quantity variation.

[33] The system control unit may perform a beam split operation for a portion of light emitted from the lighting unit, and then measure the quantity of light and a light quantity variation of the lighting unit depending on the frequency, pulsed time, driving voltage or current of the lighting unit, or the quantities of light of lighting sources of the lighting unit and light quantity variations between the lighting sources by using an optical sensor to control the quantity of light of the lighting unit or the lighting sources and the light quantity variation between the lighting sources of the lighting unit or compensate an image acquired by the image acquisition unit but distorted by due to the quantity of light and the light quantity variation.

[34] The image processing unit may use the digital data to process temporal and spatial information including the size, trajectory, speed and position of the subject.

[35] The image processing unit may be on-boarded by being embedded on a board based on a real-time OS.

[36] The system control unit may perform, based on the digital date, feedback control for generation of the subject by the subject source, adjustment of the rotating angle of the mirror, driving of an imaging operation of the image acquisition unit, and the quantity of light, impulse time and impulse timing of the lighting unit.

[37]

Advantageous Effects

[38] According to the present invention as described above, a plurality of subjects can be monitored in a high speed manner, and at the same time, a clear monitored image can be obtained from the subjects. [39]

Brief Description of the Drawings

[40] Fig. 1 is a schematic perspective view of a conventional optical monitoring system.

[41] Fig. 2 is a schematic view showing a configuration of a high speed optical monitoring system according to the present invention.

[42] Fig. 3 is a control block diagram of the high speed optical monitoring system according to the present invention.

[43] Figs. 4 to 9 are schematic views showing configurations of high speed optical monitoring systems according to other embodiments of the present invention.

[44]

Mode for the Invention

[45] Fig. 2 is a schematic view showing a configuration of a high speed optical monitoring system according to the present invention, and Fig. 3 is a control block diagram of the high speed optical monitoring system according to the present invention. As shown in the above figures, a high speed optical monitoring system 1 according to the present invention comprises a subject source support 10 for supporting at least one subject source 11 which generates at least one subject 5; an image acquisition unit 20 for monitoring and imaging the subject 5 at a fixed position; a mirror 30 and a focus compensation lens 40, which are arranged between the subject 5 and the image acquisition unit 20 for varying an optical path in a state where the subject 5 and the image acquisition unit 20 are fixed, to transmit an image of the subject 5 to the image acquisition unit 20; a lighting unit 70 for imparting a certain quantity of light to the subject 5; an image processing unit 50 for processing a digital image acquired by the image acquisition unit 20 into data; and a system control unit 60 for controlling driving of the subject source 11, the image acquisition unit 20, the mirror 30 and the lighting unit 70.

[46] The subject source support 10 supports the subject sources 11 in a line within a predetermined length range so that the subjects 5 may be positioned in an identical focal space plane F, and may include a subject source alignment unit 80 capable of moving the subject source 11 along XfYfZ axes and rotating the subject source 11 about the X/ Y/Z axes if necessary so that the subjects 5 may be finely aligned to be positioned in the identical focal space plane F.

[47] Here, the subjects 5 generated by each of the subject sources 11 may be stationary or moved in the identical focal space plane, or may be moved with their periodic time characteristics. If the subjects 5 to be monitored are liquid such as ink droplets, they may be transparent, translucent or opaque. Further, the subjects 5 may cause light to be refracted, diffracted, reflected or scattered, and are preferably monitored in a dark field or a bright field.

[48] For example, if the subject source 11 is an inkjet head and the subjects 5 are ink particles discharged from the inkjet head, each of the subjects 5 may have a size of about 5 D to 100 D and a discharged moving speed of about 1 m/s to 20 m/s. Further, the number of subjects 5 that should be monitored at a time may vary from 1 to 200, and the subjects 5 may have a periodic movement characteristic within a range of about 100 Hz to 100 kHz.

[49] The shape of the subject 5 described above is only for illustrative purposes, and the size, the moving speed, the number, the periodic time characteristic and the generation source of the subject 5 may vary.

[50] Further, the subject source alignment unit 80 is to spatially move or incline the subject source 11 to position the subjects 5 in the identical focal space plane F recognized by the image acquisition unit 20 that will be described later, and accordingly, the subject source alignment unit serves to align one or more subjects 5 generated by the subject source 11 in the identical focal space plane. More specifically, the subject source alignment unit 80 allows a stage coupled to the subject source support 10 to be moved along the X/Y/Z axes and rotated about the X/Y/Z axes so as to cause the subject source 11 to be moved along the X/Y/Z axes and moved about the X/Y/Z axes.

[51] Here, the subject source alignment unit 80 may use a conventional 6-axis manual stage scheme, for example, a 6-axis manual stage scheme in which cylindrical rods formed with threads of certain pitches are rotated to drive the stage in 6-axis directions. It will be apparent that the subject source alignment unit 80 may use an automatic alignment unit in which the stage coupled to the subject source 11 is driven in the 6-axis directions by using gears such as worm gears or bevel gears, step motors, and the like.

[52] Moreover, the subject source alignment unit 80 may be driven by means of an automatic operation by manipulating a button or the like, or may be driven for alignment by means of an automatic control of the system control unit 60 in which a preprogrammed software is used or a vision recognition system is involved. At this time, the subject source alignment unit 80 may be provided such that the respective subject sources 11 can be independently moved in the 6-axis directions.

[53] Such a subject source alignment unit 80 is set up to cause the subjects 5 generated by the subject source 11 to be positioned in the identical focal space plane F upon initial setting of the system, so that the subjects 5 can be finely imaged by the image acquisition unit 20 in a state where the subject source support 10 and the image acquisition unit 20 are aligned with each other. [54] The image acquisition unit 20 is to acquire an image by monitoring and imaging the subjects 5, and a camera having a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor) imaging device may be used as the image acquisition unit 20.

[55] Here, it is preferable to use a camera having an imaging device capable of acquiring a high-definition image with a high frame rate of 30 frame/sec, or more and a high resolution. Further, the camera preferably includes a high-magnification manual or automatic zooming lens of which magnification adjustable depending on the size of the subject 5 is 3 times or more, and may further include a doubler lens for increasing the magnification. Moreover, the camera may further include an aperture for adjusting the depth and the quantity of light.

[56] Preferably, a long-focal-length high-magnification lens may be used so that optical filters and optical components, which will be described later, including the mirror 30 or the focus compensation lens 40, may be arranged between the subject 5 and the camera, i.e., the image acquisition unit 20. At this time, the kinds and combinations of the lenses and the optical components may vary, and various modifications thereof may be freely made so far as they do not affect the spirit of the present invention.

[57] In addition, the camera and the lens may include a zooming unit and an auto focusing or manual focusing unit in order to implement precise focusing on the subject 5. At this time, it is preferred that, in order to obtain the best image quality, the optical depth of focus of the image acquisition unit 20 on the subject 5 be at least 2 times as large as the maximum length of the subject 5 to be monitored.

[58] It will be apparent that, besides the CCD camera or the CMOS camera, various image acquisition units may be used as the image acquisition unit 20 so far as they can acquire an image of the subject 5 by monitoring and imaging the subject 5.

[59] The mirror 30 includes a mirror body 31 for changing an optical path between the subject 5 and the image acquisition unit 20, and a mirror driving unit 33 for ro- tationally driving the mirror body 31.

[60] The mirror body 31 may be provided as a polygon mirror having at least a plurality of mirror surfaces as shown in Fig. 2, but if necessary as a planar mirror having a single mirror surface as shown in Fig. 4. Here, it is preferred that the mirror driving unit 33 employ a reversible motor such as a step motor capable of finely adjusting the rotational angle of the mirror body 31.

[61] In such a mirror 30, the driving of the mirror driving unit 33 changes the rotational angle of the mirror body 31 to refract the optical path directed from the subject 5 to the image acquisition unit 20. Therefore, the subject 5 to be monitored can be imaged in a state where the image acquisition unit 20 and the subject source 11 are aligned with each other. [62] At this time, the mirror driving unit 33 transmits an electrical detection signal for the rotational angle of the mirror body 31 to the system control unit 60, so that the system control unit 60 may control the driving of the mirror driving unit 33 to optimize the rotational angle of the mirror body 31.

[63] The focus compensation lens 40 compensates the distance on the optical path between the image acquisition unit 20 and the subject 5, which is changed by the mi rror 30, to synchronize focuses on the subjects 5. By doing so, the focus between the camera, i.e., the image acquisition unit 20, and at least one subject 5 which exists in the identical focal space plane F is compensated so that the image of the subject 5 can be precisely focused onto the camera, i.e., the image acquisition unit 20.

[64] Here, it is preferred that an F-theta aspheric lens is used as the focus compensation lens 40 as shown in Fig. 2. If necessary, the focus compensation lens 40 is provided as a plurality of aspheric lenses or a combination of spherical lens/aspheric lens as shown in Fig. 5, so that optical defects such as chromatic aberration and refraction aberration may be compensated. At this time, the configuration or structure of the focus compensation lens 40 may be variably changed so far as differences in the optical path between the image acquisition unit 20 and the subject 5 can be compensated.

[65] The lighting unit 70 imparts a sufficient quantity of light to the subjects 5 to ensure brightness required for the imaging of the image acquisition unit such as the camera.

[66] It is preferred that the lighting unit 70 employ a lighting device such as an impulse- type LED (light emitting diode) or an impulse-type laser diode which is associated with the movement of the subject 5, wherein as the moving speed of the subject 5 becomes faster, a sufficient quantity of light and a shorter impulse are required to obtain a clear image. Here, the conditions of the sufficient quantity of light and the shorter impulse mean a quantity of light and an impulse time by which the subjects 5 are focused onto the image acquisition unit 20 in the clearest manner through an experiment.

[67] Further, in order to ensure a sufficient quantity of light within a limited frame rate of the camera, it is preferable to select a lighting unit having higher instantaneous illuminance and a wavelength range with higher sensitivity to the imaging device of the camera so far as the subject 5 is not affected by optical sensitivity. At this time, a wavelength range in which an optical reaction to the subject 5 is prevented from being involved is preferably selected as a primary wavelength range of the lighting unit 70.

[68] The lighting unit 70 is integrally provided with the subject source support 10 as shown in Figs. 2 to 5, to entirely illuminate the subjects 5 generated by the subject sources 11, or (although not shown in the figures) a lighting unit may be provided behind the subjects 5 generated by each of the subject sources 11 so that the subjects 5 generated by each of the subject sources 11 can be independently illuminated with light. Alternatively, although not shown in the figures, the lighting unit 70 may be provided to be movable to a position where only a subject 5 corresponding to an image recognition area of the image acquisition unit 20 can be illuminated with light.

[69] Meanwhile, the lighting unit 70 may be provided at the image acquisition unit 20 to illuminate the subjects 5, as shown in Fig. 6. At this time, the lighting unit 70 may be provided as various flash lamps that can be detachably mounted to the image acquisition unit 20. Alternatively, although not shown in the figure, the lighting unit 70 may be provided as a flash lamp that is integrally contained in the image acquisition unit 20.

[70] At this time, it is preferred that the lighting unit 70 be provided as a structure connected to a lens barrel of the camera, i.e., the image acquisition unit 20, to illuminate the subject 5, as shown in Fig. 7. Here, more preferably, a reflecting plate 75 may be arranged behind the subject 5 so that the light emitted from the lighting unit 70 connected to the lens barrel can be reflected on the reflecting plate 75 to illuminate the subject 5, thereby allowing the image acquisition unit 20 to more effectively acquire an image.

[71] At this time, in order to compensate variations in the quantity of light of the lighting unit 70, a light quantity variation compensation unit 90 including at least one of a collimator, a homogenizer and a diffuser may be arranged on the optical path between the subject 5 and the image acquisition unit 20. Alternatively, when the lighting unit 70 is arranged behind the subject as shown in Figs. 2, 3 and 5, the light intensity variation compensation unit (not shown) may be arranged between the lighting unit and the subject or may be coupled to a front surface of the lighting unit.

[72] Further, although not shown in the figure, the lighting unit 70 may be separately provided at a position spaced apart by a predetermined distance from the subject 5 in order to indirectly illuminate the subject. At this time, in order to guide the light emitted from the lighting unit 70 to the subject 5 according to the position of the lighting unit 70, a lighting guide member having a bent lens barrel structure including a prism, a reflecting plate and like may be used.

[73] Furthermore, the lighting unit 70 may include a cooling device for blocking heat generated from a lighting source. Although not shown in the figure, the heat generated from the lighting unit 70 may be removed by providing the cooling device as at least one of an IR (infrared) filter and a dichroic optical filter on the optical path between the lighting unit 70 and the subject 5; or as an air-cooling type cooling device such as a cooling fan or a cooling fin, a water cooling type cooling device, or a Peltier element, which is separately installed. By doing this, the subject source 11 and the subject 5 can be effectively prevented from being deformed by the heat generated from the lighting unit 70. [74] Meanwhile, the image processing unit 50 digitalizes the image of the subject 5 acquired by the camera, i.e., the image acquisition unit 20; and uses the digitalized image data to process temporal and spatial information such as the size, trajectory, speed and position of the subject 5.

[75] The image processing unit 50 may be composed of software and hardware such as a frame grabber or a computer, and may use an ultrahigh-speed processing scheme through a real-time OS (operating system) which is conventionally represented via a board dedicated to high speed image processing.

[76] Further, the image processing unit 50 may be provided in variable forms in which the acquired image for the at least one subject 5 is processed and the information on the size, speed, trajectory, state of the subject 5 is on-boarded to the image acquisition unit 20 via the dedicated board with the real-time OS loaded thereon.

[77] Meanwhile, in the high speed optical monitoring system 1 shown in Fig. 8, it is preferred that an optical filter 91 be arranged on the optical path formed between the subject 5 and the image acquisition unit 20 to improve optical characteristics for the subject 5, thereby allowing the image acquisition unit 20 to acquire a desired high- quality image which is clearer and more accurate.

[78] At this time, the optical filter 91 may be any one of an infrared blocking filter, a polarization filter, a color filter and a band-pass filter, or a combination thereof. Further, the optical filter 91 is preferably arranged in a region of the optical path between the focus compensation lens 40 and the mirror 30. However, if necessary, the optical filter 91 may be arranged in any one of a region of the optical path between the subject 5 and the focus compensation lens 40, a region of the optical path between the focus compensation lens 40 and the mirror 30, and a region of the optical path between the mirror 30 and the image acquisition unit 20. Alternatively, a plurality of optical filters may be arranged in combination in two or more of the regions.

[79] Meanwhile, although not shown in the figure, it is preferred that an additional optical component be arranged on the optical path formed between the subject 5 and the image acquisition unit 20 in the high speed optical monitoring system 1 according to the present invention so as to acquire a high quality image.

[80] At this time, the optical component may be an expander, a collimator, a ho- mogenizer, a diffuser, or a combination thereof.

[81] Further, the optical component is preferably arranged in a region of the optical path between the focus compensation lens 40 and the mirror 30. However, if necessary, the optical component may be arranged in any one of a region of the optical path between the subject 5 and the focus compensation lens 40, a region of the optical path between the focus compensation lens 40 and the mirror 30, a region of the optical path between the mirror 30 and the image acquisition unit 20. Alternatively, a plurality of optical components may be arranged in combination in two or more of the regions.

[82] Meanwhile, as shown in Fig. 9, the high speed optical monitoring system 1 according to the present invention may further include a reference sample 95 that is arranged in the identical focal space plane F of the subject 5 to check and calibrate the optical alignment relationships between the subject 5 and the image acquisition unit 20 and between the mirror 30 and the focus compensation lens 40.

[83] At this time, the reference sample 95 is supported by a reference sample support

95a, wherein the reference sample support 95a may be provided as a structure that is detachably mounted in the identical focal space plane F of the subject 5. Further, the reference sample support 95a for supporting the reference sample 95 may be provided to be manually or automatically positioned in the identical focal space plane F of the subject 5.

[84] Preferably, the reference sample 95 has a pattern 95b formed a substrate 95c made of a transparent, translucent or opaque material and corresponding to the subject 5. The pattern 95b of the reference sample 95 is acquired as an image by the image acquisition unit 20, and correlation between the image and the actually-known size of the pattern 95b of the reference sample 95 is used to check and calibrate the optical alignment relationships between the subject 5 and the image acquisition unit 20 and between the mirror 30 and the focus compensation lens 40.

[85] Further, the pattern 95b of the reference sample 95 is used to check and calibrate the performance of the image processing unit 50.

[86] Meanwhile, the system control unit 60 controls the driving of the image acquisition unit 20, the mirror 30 and the lighting unit 70 to optimize imaging conditions such as a focusing position and a lighting state, thereby allowing the subject 5 to be imaged by the image acquisition unit 20.

[87] To this end, each of the image acquisition unit 20, the mirror 30 and the lighting unit 70 may include a driving control module 98 such as a sensor for transmitting a driving state of each of the elements to the system control unit 60. The system control unit 60 receives and processes a signal transmitted from each of the driving control modules 98, and performs, based on the signals, feedback control for the driving contro 1 of the image acquisition unit 20, the driving angle control of the mirror 30, the light quantity control of the lighting unit 70, and the like in an optimized manner.

[88] Here, among the driving control modules 98, there is a mirror control module for transmitting the driving state of the mirror 30 to the system control unit 60. As described above, the mirror control module may be a module provided in the mirror driving unit 33 itself to transmit an electrical detection signal for the rotational angle of the mirror body 31 to the system control unit 60.

[89] Alternatively, although not shown in the figures, the mirror control module may be provided as a module having a beam radiating unit for radiating light onto the mirror body 31 and a mirror-reflected light detection sensor for sensing the light reflected on the mirror body 31 and transmitting a sensed value to the system control unit 60. The system control unit 60 can control the rotational angle of the mirror body 31 by driving the mirror driving unit 33 based on the sensed value detected by the mirror-reflected light detection sensor.

[90] The signal transmitted from the mirror control module allows the system control unit 60 to optimally control the rotational angle of the mirror body 31.

[91] Further, the driving control module 98 may be provided as a lighting control module for transmitting the driving state of the lighting unit 70 to the system control unit 60, wherein the light control module may be a module such as an optical sensor for measuring emitted from the lighting unit 70 and transmitting a signal corresponding to the quantity of light detected to the system control unit 60.

[92] Here, the quantity of light of the lighting unit 70 is generated depending on the frequency, pulsed time, driving voltage or current of the lighting unit 70. As described above, the quantity of light may be detected by the lighting control module such as an optical sensor and transmitted to the system control unit 60 and the quantity of light of the lighting unit 70 is measured in a software manner by using information on brightness in the image acquired by the image acquisition unit 20 and then controlled by the system control unit 60.

[93] At this time, the system control unit 60 may correct an image that has been distorted due to the quantity of light and a light quantity variation for an image acquired by the image acquisition unit 20. Of course, as described above, after the system control unit 60 detects and measures the quantity of light and the light quantity variation of the lighting unit 70 by using an optical sensor, it may adjust the quantity of light of the lighting unit 70 and correct the distorted image depending on the light quantity variation.

[94] Based on the temporal and spatial information such as the size, trajectory, speed, position and the like of the subject 5, which have been processed by the image processing unit 50, the system control unit 60 performs feedback control for generation of the subject 5 by the subject source 11, so that the temporal and spatial physical quantities such as the size, trajectory, speed and position of the subject 5 as well as the quantity of light, impulse time, impulse timing and the like of the lighting unit 70 can be controlled in a feedback manner. To this end, the subject source 11 may include a subject generation controller 15.

[95] Next, a method of monitoring a plurality of subjects 5 by using the high speed optical monitoring system 1 according to the present invention constructed as above will be described. [96] The subjects 5 generated by the subject sources 11 are periodically moved by a predetermined moving distance in the identical focal space plane F. Here, the movement of the subjects 5 may mean that the subjects are discharged from the subject sources 11 and then dropped or discharged onto a predetermined plane.

[97] At this time, when the position of the image acquisition unit 20 is aligned, the image acquisition unit 20 precisely focuses on a region in the identical focal space plane F of the subjects 5 arranged in a line by means of an optical path A formed through the rotational angle adjustment operation for the mirror 30, which is controlled by the system control unit 60, and the focus compensation lens 40, and then precisely images the subjects 5 that are moved in the corresponding region.

[98] Then, when the position of the image acquisition unit 20 is aligned, the image acquisition unit 20 quickly and precisely focuses on other regions in the identical focal space plane F of the subjects 5 arranged in a line by means of optical paths A, B and C changed through the rotational angle adjustment operation for the mirror 30, which is controlled by the system control unit 60, and the focus compensation lens 40, and then precisely images the subjects 5 that are moved in the corresponding regions.

[99] While the rotational angle of the mirror 30 is adjusted, the subjects 5 are quickly and precisely imaged by the image acquisition unit 20 at a position where the image acquisition unit 20 and the subject source 11 are aligned with each other.

[100] Meanwhile, the images of the subjects 5 imaged by the image acquisition unit 20 are processed into digitalized image data by the image processing unit 50, so that the temporal and spatial information such as the sizes, trajectories, speeds and positions of the subjects 5 can be confirmed.

[101] Then, the system control unit 60 performs feedback control for the subject source

11 by using the subject generation controller 15 based on the digitalized temporal and spatial information on the subjects 5, so that the temporal and spatial physical quantities such as the sizes, trajectories, speeds and positions of the subjects 5 can be uniformly created. Further, the system control unit 60 can control the quantity of light, impulse time and impulse timing of the lighting unit 70.

[102] As described above, the high speed optical monitoring system according to the present invention monitors the subjects by using the optical path change operation for the mirror and the focus compensation lens in a state where the subjects and the image acquisition unit such as the camera are in stationary state, so that the subjects can be monitored and imaged precisely and at high speed, thereby controlling the subject source based on the images, resulting in active control of generation of the subjects by the subject source.

[103] According to a preferred embodiment of the high speed optical monitoring system proposed by the present invention, the subject source 11 may be an inkjet print head, the subjects 5 may be ink droplets discharged from nozzles of the inkjet print head, and the high speed optical monitoring system 1 may be an inkjet high speed monitoring system in which the inkjet droplets discharged from the nozzles are monitored in a high speed manner by using the rotatable mirror 30 and the focus compensation lens 40.

Claims

[1] A high speed optical monitoring system for monitoring at least one subject, the system comprising: at least one subject source for generating the subject; a subject source support for aligning and supporting the subject source so as to position the subject in an identical focal space plane an image acquisition unit having an imaging device for monitoring and imaging the subject at an aligned position; a mirror mounted between the subject and the image acquisition unit such that a rotational angle of the mirror can be changed; a focus compensation lens arranged between the subject and the mirror; an image processing unit for processing an image acquired by the image acquisition unit into digital data; a lighting unit for illuminating the subject; and a system control unit for controlling the lighting unit and driving of the subject source, the image acquisition unit and the mirror.

[2] The high speed optical monitoring system as claimed in claim 1, wherein said at least one subject comprises a plurality of subjects, and the subjects are stationary or moved, or are generated in a periodic or quasi-periodic manner and moved dynamically.

[3] The high speed optical monitoring system as claimed in claim 1, further comprising a subject source alignment unit coupled to the subject source support so as to move the subject source along X/Y/Z axes and to tilt or rotate the subject source about the X/Y/Z axes.

[4] The high speed optical monitoring system as claimed in claim 1, wherein the image acquisition unit is a camera having a CCD or CMOS imaging device.

[5] The high speed optical monitoring system as claimed in claim 1, wherein the mirror comprises: a mirror body composed of a planar mirror having at least one single mirror surface; and a mirror driving unit for rotating the mirror body within a certain rotational angle.

[6] The high speed optical monitoring system as claimed in claim 1, wherein the mirror comprises: a mirror body composed of a polygon mirror having a plurality of mirror surfaces; and a mirror driving unit for rotating the mirror body within a certain rotational angle.

[7] The high speed optical monitoring system as claimed in claim 1, wherein the focus compensation lens is provided as a single F-theta aspheric lens, a plurality of aspheric lenses, or a combination of spherical lens/aspheric lens.

[8] The high speed optical monitoring system as claimed in claim 1, wherein the subject is moved, and the lighting unit employs an impulse-type light emitting diode or laser diode associated with the movement of the subject that is moved.

[9] The high speed optical monitoring system as claimed in claim 1 or 8, further comprising a light quantity variation compensation unit provided on an optical path between the subject and the image acquisition unit so as to compensate a light quantity variation of the lighting unit.

[10] The high speed optical monitoring system as claimed in claim 1 or 8, wherein the lighting unit is provided behind the subject or in the image acquisition unit to illuminate the subject, and if the lighting unit is provided in the image acquisition unit, a reflecting plate is provided behind the subject.

[11] The high speed optical monitoring system as claimed in claim 1, wherein the lighting unit comprises an air cooling type or water cooling type cooling device for blocking heat generated from a lighting source.

[12] The high speed optical monitoring system as claimed in claim 11, wherein the cooling device comprises at least one of an IR (infrared) filter and a dichroic optical filter.

[13] The high speed optical monitoring system as claimed in claim 11, wherein the cooling device is a Peltier element.

[14] The high speed optical monitoring system as claimed in claim 1, wherein at least one optical filter of an infrared blocking filter, a polarization filter, a color filter and a band pass filter is provided on an optical path between the subject and the image acquisition unit.

[15] The high speed optical monitoring system as claimed in claim 5, further comprising a reference sample arranged in the identical focal space plane so as to check and calibrate optical alignment relations between the subject and the image acquisition unit and between the mirror body and the focus compensation lens.

[16] The high speed optical monitoring system as claimed in claim 15, further comprising a reference sample support arranged in the identical focal space plane so as to support the reference sample, wherein the reference sample support is detachably coupled in the identical focal space plane or is installed to be movable between a position at which the reference sample support is arranged in the identical focal space plane and another position out of the identical focal space plane.

[17] The high speed optical monitoring system as claimed in claim 16, wherein the reference sample support is positioned manually or automatically in the identical focal space plane.

[18] The high speed optical monitoring system as claimed in any one of claims 15 to

17, wherein the reference sample has a pattern corresponding to the subject and formed on a substrate made of a transparent, translucent or opaque material.

[19] The high speed optical monitoring system as claimed in claim 18, wherein the pattern of the reference sample is acquired as an image by the image acquisition unit, so that correlation between the image and the size of the pattern can be used to calibrate the optical alignment relations between the subject and the image acquisition unit and between the mirror and the focus compensation lens as well as to calibrate the image processing performance.

[20] The high speed optical monitoring system as claimed in claim 5, wherein the mirror driving unit transmits an electrical detection signal for the rotational angle of the mirror body to the system control unit, and the system control unit receives the electrical detection signal for the rotation angle of the mirror body and controls driving of the mirror driving unit so as to control the rotational angle of the mirror body.

[21] The high speed optical monitoring system as claimed in claim 5, further comprising a beam radiating unit for radiating light onto the mirror body and a mirror-reflected light detection sensor for sensing the light reflected on the mirror body, wherein the system control unit controls driving of the mirror driving unit based on a sensed value transmitted from the mirror-reflected light detection sensor to control the rotational angle of the mirror body.

[22] The high speed optical monitoring system as claimed in claim 1, wherein the system control unit acquires the quantity of light and a light quantity variation of the lighting unit depending on the frequency, pulsed time, driving voltage or current of the lighting unit, or the quantities of light of lighting sources of the lighting unit and light quantity variations between the lighting sources by the image acquisition unit, and then measures the quantity of light and the light quantity variation in a software manner, to control the quantity of light of the lighting unit or the lighting sources and the light quantity variation between the lighting sources of the lighting unit or compensate an image acquired by the image acquisition unit but distorted by due to the quantity of light and the light quantity variation.

[23] The high speed optical monitoring system as claimed in claim 1, wherein the system control unit performs a beam split operation for a portion of light emitted from the lighting unit, and then measures the quantity of light and a light quantity variation of the lighting unit depending on the frequency, pulsed time, driving voltage or current of the lighting unit, or the quantities of light of lighting sources of the lighting unit and light quantity variations between the lighting sources by using an optical sensor, to control the quantity of light of the lighting unit or the lighting sources and the light quantity variation between the lighting sources of the lighting unit or compensate an image acquired by the image acquisition unit but distorted by due to the quantity of light and the light quantity variation.

[24] The high speed optical monitoring system as claimed in claim 1, wherein the image processing unit uses the digital data to process temporal and spatial information including the size, trajectory, speed and position of the subject.

[25] The high speed optical monitoring system as claimed in claim 24, wherein the image processing unit is on-boarded by being embedded on a board based on a real-time OS.

[26] The high speed optical monitoring system as claimed in claim 1, wherein the system control unit performs, based on the digital date, feedback control for generation of the subject of the subject source, adjustment of the rotating angle of the mirror, driving of an imaging operation of the image acquisition unit, and the quantity of light, impulse time and impulse timing of the lighting unit.