WO2009002467A2

WO2009002467A2 - Panoramic endoscopic visualization system

Info

Publication number: WO2009002467A2
Application number: PCT/US2008/007783
Authority: WO
Inventors: Amir Belson; Michael Patrick O'neil
Original assignee: Amir Belson; Michael Patrick O'neil
Priority date: 2007-06-22
Filing date: 2008-06-23
Publication date: 2008-12-31
Also published as: WO2009002467A3

Abstract

The invention provides an endoscopic visualization system utilizing a selectively reflective element that allows wide-angle and/or retrograde viewing and forward viewing with an endoscope having a single imaging camera or other imaging means. The endoscopic visualization system can be switchable from a forward-viewing mode to a wide-angle or retrograde viewing mode or to a mode that allows simultaneous viewing of forward and wide-angle and/or retrograde images.

Description

PANORAMIC ENDOSCOPIC VISUALIZATION SYSTEM

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 60/936,910, filed on June 22, 2007. This and all patents and patent applications referred to herein are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to endoscopes and endoscopic visualization systems. More particularly, it relates to an endoscopic visualization system that provides broad panoramic viewing, including selective viewing in the lateral and retrograde or rearward directions.

BACKGROUND OF THE INVENTION

Colonoscopy is widely regarded as the "gold standard" for detection of abnormalities in the colon. However, research has revealed that 12-24% of polyps and a significant number of cancers can be missed during colonoscopy, especially if they lie behind haustral folds in the colon wall. (Annals of Internal Medicine 2004; 141:352-360; Gastrointestinal Endoscopy 2005;61 :385-391; Gastroenterology 1997;112:24-28.)

In a laboratory bench study (Gastrointestinal Endoscopy 2006;63:AB103) and a pilot study in humans (Endoscopy 2008 Jun;40(6):478-82), it has been demonstrated that the detection rate of polyps and adenomas by colonoscopy can be significantly increased by combining a retrograde view of the colon with the forward view of a standard colonoscope. The device used in these studies (Third Eye Retroscope from Avantis Medical Systems, Inc.) is an auxiliary endoscope device that is inserted through the instrument channel of a colonoscope to provide a retrograde view of the colon. While this device has shown efficacy in preliminary testing, there are a number of drawbacks to this approach. The method requires manipulation of a second endoscope device, which will add to the complexity of the procedure. The device utilizes a second visualization system with a separate imaging camera, which will add to the overall cost of the equipment used for the procedure. The retrograde image from the device is only available during withdrawal of the colonoscope, not during insertion into the colon. In addition, the device occupies the instrument channel of the colonoscope, which will interfere with the ability to perform diagnostic or therapeutic procedures through the instrument channel, such as biopsy or polypectomy.

Another device (Aer-O-Scope from GI View Ltd.) is a pneumatically propelled colonoscope that includes a 360 degree imaging system (Omni vision) in addition to a forward- viewing camera. The 360 degree imaging system captures images of the colon around the device, but does not provide a true retrograde view of the colon. In addition, the inflatable balloon that is required for the pneumatic propulsion mechanism flattens polyps or other lesions to the wall of the colon as it passes, which may interfere with the ability to identify or diagnose the polyps and lesions. The current model of the device is for diagnostic purposes only and therefore does not have any instrument channel to perform additional diagnostic or therapeutic procedures, such as biopsy or polypectomy. This may significantly increase the overall cost of the procedure because a second colonoscopy will be needed for biopsy and/or polypectomy using a standard colonoscope if any suspicious lesions are found during the diagnostic screening.

Although these devices represent advances in the technology, further improvements are needed to provide effective, convenient and cost-efficient expanded side viewing and retrograde viewing in conjunction with standard forward-viewing colonoscopy. It would be desirable therefore to provide an endoscopic visualization system that can augment the capabilities of a standard colonoscope by providing expanded side views and/or retrograde views without the cost and inconvenience of a secondary device or a second imaging camera. It would also be desirable to provide an endoscopic visualization system that can be retrofitted to existing colonoscopes or built into new colonoscopes. The endoscopic visualization system will preferably be compatible with other diagnostic and therapeutic functions of the colonoscope, such as biopsy and polypectomy and will be compatible with current and future mechanisms for steering, navigation or propulsion of the colonoscope. The endoscopic visualization system of the present invention will also find utility in other areas of endoscopy for medical, scientific and industrial applications.

SUMMARY OF THE INVENTION

In keeping with the foregoing discussion, the present invention takes the form of an endoscopic visualization system that utilizes a selectively reflective element that allows wide-angle and/or retrograde viewing and forward viewing with an endoscope utilizing a single imaging camera or other imaging means. The endoscopic visualization system can be switchable from a forward- viewing mode to a wide-angle or retrograde viewing mode or to a mode that allows simultaneous viewing of forward and wide-angle and/or retrograde images.

In one embodiment, the selectively reflective element comprises an electrochromic material that is switchable between a reflective state and a transmissive or transparent state. In another embodiment, the selectively reflective element comprises a rotating reflector that rotates within the field of view of the endoscope to create a scanned forward- viewing image and a scanned wide-angle and/or retrograde-viewing image. In another embodiment, the selectively reflective element comprises a slotted rotating disk with one or more reflectors and one or more transparent or open portions to create a scanned forward-viewing image and a scanned wide-angle and/or retrograde-viewing image. In another embodiment, the selectively reflective element comprises a plurality of rotating shutters that allow the endoscopic visualization system to alternate between a forward- viewing image and a wide-angle and/or retrograde-viewing image. In yet another embodiment, the selectively reflective element comprises a polarizing reflective element that is used with a polarization separating beamsplitter to provide simultaneous forward-viewing and wide-angle and/or retrograde-viewing images. The imaging optics can be arranged to use one or two imaging cameras. Various embodiments can be used with an extension cap that extends the working channels of the endoscope to a point distal to the reflective element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. IA and IB illustrate a distal end of an endoscope with an active reflector system for selective rearward viewing. FIG. 2 illustrates a distal end of an endoscope with a reflector cap that encloses an angled active reflector and extensions for the working channel, air and water ports of the endoscope.

FIGS. 3 A and 3B illustrate a distal end of an endoscope with a convex active reflector system for selective rearward viewing.

FIGS. 4A and 4B illustrate a distal end of an endoscope with an active reflector system that can be selective stowed or deployed from the distal end of the endoscope.

FIG. 5 illustrates a distal end of an endoscope with a rotating reflector positioned distally to the optics and lighting systems of the endoscope.

FIGS. 6A and 6B illustrate the view provided by the rotating reflector of FIG 5.

FIGS. 7A and 7B illustrate image display options for the endoscopic visualization system of FIG 5.

FIGS. 8A, 8B and 8C illustrate a retrograde imaging device with an active reflector that is sized and configured for insertion through a working channel of an endoscope.

FIG. 9 illustrates a distal end of an endoscope with a fixed position electrochromic reflector for selective rearward viewing.

FIGS. 1OA and 1OB illustrate a distal end of an endoscope with a fixed position electrochromic reflector for selective rearward viewing.

FIG. 11 illustrates a distal end of an endoscope with a reflector cap that has an electrochromic reflector on a distal surface and extensions for the working channels of the endoscope. FIG. 12 illustrates a distal end of an endoscope with a rotating reflector positioned distally to the optics and lighting systems of the endoscope.

FIG. 13 illustrates a distal end of an endoscope with a rotating reflector positioned distally to two sets of optics and lighting systems.

FIG. 14A illustrates a top view and FIG. 14B illustrates a bottom view of a slotted reflector for use with the endoscopes of FIGS. 12 and 13.

FIG. 15 is a table listing the different views provided by the slotted reflector of FIGS. 14A and 14B.

FIG. 16 illustrates a distal end of an endoscope with rotatable reflective shutters for selective rearward viewing.

FIG. 17 illustrates a single rotatable reflective shutter.

FIGS. 18 A, 18B and 18C illustrate three positions of the rotatable reflective shutters.

FIG. 19 illustrates a rotatable reflective shutter with shaped reflective surfaces.

FIGS. 20 and 21 illustrate a distal end of an endoscope with a visualization system that utilizes polarized light for simultaneous forward and rearward viewing.

FIG. 22 shows how the polarized reflector of the endoscopic visualization system of FIGS. 20 and 21 can be mapped onto a Fresnel lens.

FIG. 23 shows an alternative optical arrangement for the endoscopic visualization system of FIGS. 20 and 21. DESCRIPTION OF THE INVENTION

FIGS. IA and IB illustrate a distal end of an endoscope 102 having an endoscopic visualization system 100 with an active reflector element 104 for selective rearward viewing. An active reflector refers to a reflector having the ability to shift between reflective and transmissive or transparent modes through application of a suitable stimulation. An active reflector may be a switchable mirror. An active reflector may contain an array of switchable reflective optical components such as those described by Janssen, et al in U.S. Patent Application Publication 2003/0108276. One example of an active reflector would be a reflector formed from an electrochromic material that controllably switches between a transmissive mode and reflective mode. Examples of electrochromic materials are described in, for example, U.S. Patent 7,042,615.

In this illustrative embodiment, the active reflector element 104 is in the configuration of a conical ring. The reflective surface 110 of the conical ring may have a constant conical angle or it may have a convex curvature to provide wider angle viewing. Other geometries of the reflector element 104 are also possible. The reflector element 104 may be supported on the distal end of the endoscope 102 with one or more legs 116 that are preferably transparent or low profile so that they do not interfere with imaging by the endoscopic visualization system 100. FIG. IA illustrates the reflector 104 in a reflective mode so that the rearward view 112 is visible to the camera 106 of the endoscope 102. FIG. IB illustrates the reflector 104 in a transmissive or transparent mode so that the forward view 114 is visible to the camera 106 of the endoscope 102. A control system may be used to shift the reflector mode automatically, semi-automatically or under the control of a user. The reflector mode can be switched rapidly enough so that the user will effectively get a continuous rearward view and forward view using a single camera 106 or other imaging means, such as a fiberoptic bundle or rod optics. The rearward (FIG. IA) and forward (FIG. IB) views provided by the endoscopic visualization system 100 may be combined into a single integrated view providing a user a comprehensive view of the surroundings of the instrument. FIG. 2 illustrates a distal end of an endoscope 102 with a reflector cap 120 that encloses an angled active reflector 104 and extensions 122_? 124 for the working channel 126, air and water ports 128 of the endoscope 102. The reflector cap 120 includes an angled active reflector 104 adapted and positioned to work cooperatively with the existing light and camera 106 on the endoscope 102. The angled active reflector 104 provides forward/rearward viewing as described above. As illustrated, the working channel 126, air and water ports 128 are not impacted by the placement of the reflective cap 120 on the distal end of the endoscope 102. Preferably, the reflector cap 120 and the working channel extension 122 and the air and water port extension(s) 124 are made from transparent material so that they do not interfere with imaging by the endoscopic visualization system 100.

FIGS. 3 A and 3B illustrate a distal end of an endoscope 102 with a convex active reflector 130 for selective rearward viewing. The convex active reflector 130 may have a spherical or parabolic curvature or other preferred geometry. The convex active reflector 130 may be supported by a thin support wire 132 inserted through one of the channels of the endoscope 120 as shown, or may be supported by one or more transparent legs or a reflector cap attached to the distal end of the endoscope 102 as described above. When the reflector 130 is active, a rearward view 112 is provided as illustrated in FIG. 3 A. When the reflector 130 is inactive, a forward view 114 is visible to the user as shown in FIG. 3B. As with all of the embodiments of the invention described herein, the video stream, digital images or other visual information provided from the forward and rearward views may be displayed separately and/or integrated into a single unified view.

FIGS. 4A and 4B illustrate a distal end of an endoscope with an active reflector system 134 that can be selective stowed or deployed from the distal end of the endoscope 102. A scissors mechanism 136 or other deployment mechanism can be used to extend and retract the reflector 134. The active reflector 134 may be flat, as in the example shown, or another geometry, such ring-shaped or convexly curved as in the other examples above.

FIG. 5 illustrates a distal end of an endoscope with a rotating reflector 140 positioned distally to the camera optics 106 and lighting systems of the endoscope 102. The reflector 140 is mounted on a rotating shaft 144 and is rotated by a motor 146 that may be located within the endoscope 102 or proximal to it. The reflector 140 sits underneath a protective cover 142. The cover 142 is transparent to the wavelengths used by the camera optics 106 and lighting system. Alternatively, a transparent reflector cap 120 similar to the one in FIG. 2 may be used. The reflector 140 may cover as much as 180 degrees of the field of view of the endoscope camera 106 or it may be smaller to intercept a smaller portion of the field of view. The reflector 140 may be flat or curved, for example with a convex curve for imaging a wider angle view. Optionally, the reflector 140 may have a plurality of regions or facets with different angles or curves to view in different direction. For example, one reflector region could be directed laterally and another could be directed in a retrograde direction.

FIGS. 6 A and 6B illustrate the simultaneous forward 114 and rearward 112 views provided by the rotating reflector 140 in the endoscopic visualization system 100 of FIG 5. FIG. 6 A shows that, when the rotating reflector 140 is on the left, the left side of the view is reflected rearward 112 while the right side provides a forward view 114. FIG. 6B shows that, when the reflector 140 rotates 180 degrees over to the right side, the reflector 140 provides the rearward view 112 on the right side and a forward view 114 is provided on the left side. The continuous rotation of the reflector 140 creates scanned or sweeping forward 114 and rearward 112 views, effectively providing simultaneous forward and retrograde imaging with one camera 106. Alternatively, the reflector 140 can be rotated discretely, for example in 180 degree increments, with the camera 106 taking "snapshots" toward the right and left with the reflector 140 while the reflector 140 is momentarily stationary.

The scanned forward 114 and rearward 112 views undergo a suitable image processing to provide an integrated output. The forward and rearward images may be displayed on separate monitors or may be integrated into a single display on one monitor. Such a step can be synchronization of the image shown with the position of the reflector. The front image can be projected on a separate picture from the rear image. Different wavelengths of light may be used, for example for diagnosing suspected lesions. The different wavelength images may be displayed separately or integrated into a single image, for example using false colors to display the results of tissue analysis on the display. FIGS. 7A and 7B illustrate image display options for the endoscopic visualization system of FIG 5.

FIG. 8A illustrates a retrograde imaging device 150 with an active reflector 152 that is sized and configured for insertion through a working channel of an endoscope. A transparent cover 154 encloses the reflector 152 and provides a smooth, atraumatic distal end. The active reflector 152 is switchable between clear and reflective modes. FIG. 8B illustrates how the clear mode allows for a forward view 114. FIG. 8C illustrates how a reflective or active mode provides a rearward view 112. Alternatively, the device could utilize a rotating reflector as described herein.

FIG. 9 illustrates a fixed electrochromic reflector 160 placed on the optics 106 or illumination components of an endoscope 102. Top surface 162 of the reflector 160 is made of an electrochromic material and the sidewalls 164 are preferably transparent. The top surface 162 may have different shapes to alter the rearward view provided when the reflector 160 is active.

FIG. 1OA illustrates the endoscopic visualization system of FIG 9 with the electrochromic reflector 160 in a transmissive state. FIG. 1OB illustrates the endoscopic visualization system of FIG 9 with the electrochromic reflector 160 in a reflective state.

FIG. 11 illustrates a distal end of an endoscope 102 with a reflector cap 170 that has an electrochromic reflector 172 formed on a distal surface and extensions 122, 124 for the working channels 126, 128 of the endoscope 102. Optionally, the channel extensions 122, 124 may be provided with a hatch or cover 174 that is closed when not in use. The electrochromic reflector 172 may be provided atop a transparent cylindrical base 176.

FIG. 12 illustrates a distal end of an endoscope 102 with a rotating reflector 180 positioned distally to the imaging optics 106 and light source 107 of the endoscope 102. In this example, the endoscope 102 has a single set of imaging optics 106 and light source 107. The rotating reflector 180 is supported on a rotating shaft 182 that extends through a working channel or a dedicated channel 186 internal or external to the endoscope 102. A transparent cover 184 provides a smooth, atraumatic tip over the rotating reflector 180. FIG. 13 illustrates an example of a rotating reflector 180 in use with an endoscope 102 having two pairs of lighting 107 and imaging optics 106.

FIG. 14A illustrates a top view and FIG. 14B illustrates a bottom view of a slotted rotating reflector 180 for use with the endoscopes of FIGS. 12 and 13 or with any of the endoscopic visualization systems described herein. FIG. 14A illustrates the top view of the slotted rotating reflector 180 having four open slots, 1, 2, 3, and 4. More or fewer open slots may be provided and the slots may or may not be of equal size or shape. The bottom view in FIG. 14B illustrates the reflective surfaces A, B, C and D placed between the open slots 1, 2, 3 and 4. Each of the reflective surfaces A, B, C, D may have a different angle and/or curvature to provide different degrees of lateral and rearward viewing. As the reflector 180 rotates, the view alternates between the forward view presented by the open slots 1, 2, 3, 4 and the angled or rearward views provided by the reflective surfaces A, B, C, D.

FIG. 15 is a table listing one example of the different views provided by the slotted rotating reflector 180 of FIGS. 14A and 14B. Numerous other combinations of views are also possible. As with all of the embodiments described herein, the various views can be displayed separately or combined into an integrated view.

FIG. 16 illustrates another alternative endoscopic visualization system for providing a wider endoscopic view. FIG. 16 shows a distal end of an endoscope 102 with rotatable reflective shutters 190 for selective rearward viewing. A plurality of reflective shutters 190 is placed on an end cap 192 on the endoscope 102. A single rotatable reflective shutter 190 is illustrated in FIG. 17. Each of the rotatable reflective shutters 190 rotates about a shaft 194 and has a first reflective surface 196 and a second reflective surface 198. The reflective shutters 190 may be thin so that when rotated up out of the field of view they block only a small percentage of the viewable field.

FIGS. 18A, 18B and 18C illustrate three positions of the rotatable reflective shutters 190. When the reflective shutters 190 are in the position shown in FIG. 18 A, the first reflective surface 196 faces the camera 106 to provide a rearward view. Continued rotation of the reflective shutters 190 to the position shown in FIG. 18B allows a forward view. Further rotation to the position shown in FIG. 18C provides a reflected rearward view from the second reflective surface 198 of the reflective shutters 190. The reflective shutters 190 may be rotated continuously or they may be rotated incrementally or flipped back and forth, pausing the rotation briefly to take "snapshots" of the forward and lateral and/or rearward images. This can be done rapidly enough to provide the appearance of continuous images in all directions simultaneously. The first reflective surface 196 and the second reflective surface 198 may have the same shape as shown or may have different angles and/or curvatures to provide different lateral and/or rearward views. FIG. 19 illustrates an embodiment of a rotatable reflective shutter 190 where the rotating mirror reflective surfaces 196, 198 are angled. Other angles or curves, such as convex and concave, are possible and may be provided as desired. Image systems and reflector and other details described in U.S. Patent Application Publication 2005/0168616 may also be adapted and used in the systems described herein.

FIGS. 20 and 21 illustrate a distal end of an endoscope 201 with a visualization system that utilizes polarized light for simultaneous forward and rearward viewing. FIG. 20 shows an arrangement where an apparatus such as an endoscope 201 or similar device, deploys two bundles or rings of illumination fibers. Forward-illuminating fibers 202 disposed about the central axis of the endoscope 201 project light forward with a broad numerical aperture 203. The ends of the fibers 202 are cleaved perpendicular to their length in the standard manner. A second bundle or ring of rearward-illuminating fibers 205 has ends that are cleaved at an angle 206 so as to retroreflect light substantially backward with a broad numerical aperture 207. Reflector element 208 is a panoramic annular reflector for P-polarized light, but is transmissive to S- polarized light - the opposite arrangement is also possible. A polarization separating beamsplitter 209 directs S-polarized light to detector 214 whereas P-polarized light is directed to detector 212. The detectors 212, 214 are preferably CCD camera detectors or the like.

FIG. 21 shows that P-polarized light rays 211 originating from the retrograde direction are reflected by the reflector element 208 toward the polarization separating beamsplitter 209, which reflects the rays 211 toward the retrograde image detector 212 to form a rearward-facing image. S-polarized light rays 210 originating from the retrograde direction pass through the reflector element 208 and are not directed toward the detectors 212, 214. S-polarized light rays 213 originating from the forward direction pass through the reflector element 208 and through the polarization separating beamsplitter 209 toward the forward image detector 214 to form a forward-facing image. P-polarized light rays 215 originating from the forward direction are reflected away by the reflector element 208 and are not directed toward the detectors 212, 214. In this way, the clean separation of forward-originating and backward-originating rays is achieved.

FIG. 22 shows that optical element 208, such as the one shown in FIGS. 20 and 21, may be mapped onto a Fresnel lens 220 which is substantially planar, allowing for a more compact imaging system. The Fresnel lens 220 may be coated to transmit S-polarized light 210, 213, and reflect P-polarized light 211.

FIG. 23 shows an alternative optical arrangement for the endoscopic visualization system of FIGS. 20 and 21. Instead of separate detectors 212, 214 as shown in FIGS. 20 and 21, the system of FIG. 23 utilizes a single detector 233 with two detector areas 231, 232 for forming forward and rearward images. This can also be accomplished with two separate coplanar detectors. S- polarized light rays 213 will pass through the beamsplitter 209 and impinge on detector area 231. P-polarized light rays 211 will be reflected by the beamsplitter 209 onto a specular reflector 230 and directed to detector area 232.

Optionally, the reflector element 208 of FIG. 21 may be configured to allow switching of its polarization state so as to be either substantially reflective or substantially transmissive to P or S polarization on demand. Such devices as Pockels cells or Kerr cells are well known examples of means with which to switch their reflective or transmissive polarization states on demand.

Embodiments provided via a dedicated or working channel may be configured as described in U.S. Patent Application Publication 2006/0149129, incorporated herein by reference in its entirety and for all purposes. Numerous details of endoscopic visualization systems are provided by U.S. Patent Application Publication US 2004/0249247; U.S. Patent 6,736,773; each of which is incorporated herein by reference in its entirety and for all purposes. While the present invention has been described herein with respect to the exemplary embodiments and the best mode for practicing the invention, it will be apparent to one of ordinary skill in the art that many modifications, improvements and subcombinations of the various embodiments, adaptations and variations can be made to the invention without departing from the spirit and scope thereof.

Claims

1. An endoscopic visualization system, comprising: imaging means; and a selectively reflective element positioned in a field of view of the imaging means, the selectively reflective element being switchable between a reflective state and a transmissive state.

2. The endoscopic visualization system of claim 1, wherein the selectively reflective element comprises an electrochromic material switchable between a reflective state and a transmissive state.

3. The endoscopic visualization system of claim 1, further comprising: display means for simultaneously displaying a forward image and a reflected image.

4. The endoscopic visualization system of claim 1, further comprising: an endoscope body having at least one working channel and an extension of the at least one working channel to a point distal to the selectively reflective element.

5. The endoscopic visualization system of claim 1, wherein the selectively reflective element has a convex reflective surface.

6. The endoscopic visualization system of claim 1, wherein the selectively reflective element is configured as a conical ring.

7. An endoscopic visualization system, comprising: imaging means; at least one reflective element positioned in a field of view of the imaging means thereby dividing the field of view of the imaging means into a reflected portion and a forward-viewing portion; means for moving the reflective element within the field of view of the imaging means thus creating a scanned reflected image and a scanned forward-viewing image; means for reconstructing the scanned reflected image into a complete reflected image; and means for reconstructing the scanned forward-viewing image into a complete forward image.

8. The endoscopic visualization system of claim 7, wherein the reflective element rotates about an axis within the field of view of the imaging means.

9. The endoscopic visualization system of claim 7, further comprising: display means for simultaneously displaying the forward-viewing image and the reflected image.

10. The endoscopic visualization system of claim 7, wherein the at least one reflective element is mounted on a rotating member that further comprises at least one opening or transparent portion.

11. The endoscopic visualization system of claim 10, wherein a plurality of reflective elements are mounted on the rotating member.

12. The endoscopic visualization system of claim 11, wherein the plurality of reflective elements are mounted at different angles with respect to an axis of rotation of the rotating member.

13. The endoscopic visualization system of claim 12, wherein scanned reflected images created by the plurality of reflective elements are reconstructed into a single reflected image.

14. The endoscopic visualization system of claim 12, wherein scanned reflected images created by the plurality of reflective elements are reconstructed into separate reflected images.

15. An endoscopic visualization system, comprising: imaging means; at least one shutter having at least one reflective surface positioned in a field of view of the imaging means; the shutter being movable from a first position, wherein the reflective surface faces the imaging means for directing a reflected image to the imaging means, to a second position, wherein a narrow edge of the shutter faces the imaging means allowing the imaging means to capture a forward-viewing image.

16. The endoscopic visualization system of claim 15, comprising a plurality of shutters.

17. The endoscopic visualization system of claim 16, wherein each shutter rotates about an axis within the field of view of the imaging means.

18. The endoscopic visualization system of claim 16, wherein each shutter has a first reflective surface and a second reflective surface.

19. The endoscopic visualization system of claim 15, wherein the first reflective surface and the second reflective surface have different reflector geometries.

20. An endoscopic visualization system, comprising: imaging means; a polarizing reflector positioned in a field of view of the imaging means, wherein the polarizing reflector reflects P polarized light and transmits S polarized light; a polarizing beam splitter arranged between the polarizing reflector and the imaging means, wherein the polarization separating beamsplitter separates P polarized light from S polarized light, thus forming a reflected image from the P polarized light and a forward-viewing image from the S polarized light.

21. The endoscopic visualization system of claim 20, wherein the imaging means comprises a first detector element arranged to detect the P polarized light and a second detector element arranged to detect the S polarized light.

22. The endoscopic visualization system of claim 20, wherein the imaging means comprises a single detector element arranged so that the S polarized light from the polarization separating beamsplitter is received on a first portion of the detector element, and wherein a reflector is arranged to direct the P polarized light from the polarization separating beamsplitter to a second portion of the detector element.

23. The endoscopic visualization system of claim 20, wherein the polarizing reflector has a conical geometry.

24. The endoscopic visualization system of claim 20, wherein the polarizing reflector has a curved conical geometry.

25. The endoscopic visualization system of claim 20, wherein the polarizing reflector comprises a Fresnel lens coated with a polarizing reflective coating.