UNIVERSAL ENDOSCOPE VIDEO ADAPTOR WITH ZOOM

Abstract: An improved adaptor (10) for coupling a video camera (14) to an endoscope (12), a borescope (12), or the like includes a focusing mechanism (32), and an independent zoom or magnification variation adjustment (34) mechanism. The zoom mechanism (32) will move two lens groups (40, 42) along an optical path simultaneously, but at different speeds. Each lens group (40, 42) preferably includes a pair of lenses (40a, 40b, 42a, 42b) affixed together as a doublet. By controlling the position of the doublets (40, 42) relative to a pair of focusing lenses (48, 50), the present adaptor (10) provides an optically compensated zoom mechanism (34) which allows changes in the magnification of the adaptor (10) throughout a wide magnification range without having to refocus the adaptor (10).

Description: UNIVERSAL ENDOSCOPE VIDEO ADAPTOR WITH ZOOM CROSS-REFERENCES TO RELATED APPLICATIONS This application is a Continuation-in-Part of Application No. 08/988,502, filed on December 10, 1997 (Attorney Docket No. 14766-000900). The full disclosure of this Application is hereby incorporated by reference for all purposes. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to optical imaging devices and methods, and more particularly, provides an adaptor for coupling a video camera to an optical viewing device such as an endoscope, a borescope, or the like, especially for viewing and documenting images from within a patient body. Endoscopes are often used by physicians to view internal tissues of a patient body. Traditionally, physicians have observed internal body tissues through an eye piece of the endoscope. Although this allows physicians to diagnose and optically direct therapies of these internal tissues, increasingly complex minimally invasive internal surgical procedures have recently been developed, resulting in physicians viewing internal tissues through endoscopes for an extending period of time. Adaptors have recently become available which attach endoscopes to video cameras, thereby allowing physicians to view images of the internal body tissues on a standard viewing screen. This can significantly increase the comfort of the physician during the procedure, improving both efficiency and safety of endoscopically directed minimally invasive surgical procedures. These adaptors also facilitate documenting the images of the internal tissues (and internal surgical procedures) for future reference. One disadvantage of known endoscopic video adaptors is that it is often difficult to change the magnification of the video image during the procedure. For example, in laparoscopic cholecystectomy it is generally desirable to begin the surgical procedure while viewing a video image which is at quite low magnification. Low magnification presents a wide, panoramic view of the surgical area, and thereby facilitates optically directing the safe introduction of the various trocars and other instruments which will be used during cholecystectomy. However, as the cholecystectomy procedure continues, it would be desirable to increase the magnification. More specifically, the surgeon will generally desire a closer, more detailed view when dissecting the cystic artery, dissecting the cystic duct, and when introducing the cholangiogram catheter into the cystic duct. To provide such detailed viewing, quite high magnification of the video image would be desirable. Furthermore, when dissecting the gall bladder from the liver bed, it would be desirable for the surgeon to operate while viewing a video image at a mid-range magnification. In other words, it is generally advantageous to allow a physician to operate at a variety of magnifications during the course of a single surgical procedure. Also, a wide variety of endoscopes with different view angles are used in various surgical procedures. Each scope, however, is required to have a video adaptor with a specific magnification for the video camera to be used. What is necessary, therefore, is a universal zoom video adaptor which can accommodate all endoscope view angles and any camera of choice. Many video adaptors now being used with endoscopes are restricted to a single magnification level, the adaptors often having a fixed field of view. Video adaptors having some zoom capabilities are available commercially. Unfortunately, these commercially available zoom video adaptors generally require refocusing of the video image each time the magnification has changed. This increases the amount of time required for an endoscopically directed procedure, and can substantially increase patient risk, particularly during the time period the image is out of focus. To overcome these disadvantages, it would be desirable to provide improved devices for coupling a video camera and/or video system to an endoscopy, borescope, or the like. 2. Description of the Background Art U.S. Patent No. 4,862,199 describes an adjustable adaptor for a borescope and a film/video camera. A zoom lens adaptor for an endoscopic camera is described in U.S. Patent No. 4,781,448. An endoscopic zoom lens is described in U.S. Patent No. 5,418,645. Optical systems for endoscopes are also described in U.S. Patent Nos. 5,245,745 and 5,575,757. An eye piece mechanism for an endoscope is described in U.S. Patent No. 5,078,503. A lens mount assembly is described in U.S. Patent No. 5,194,992, while a zoom lens mechanism is described in U.S. Patent No. 3,906,529. A zoom image coupler is commercially available from Precision Optics Corporation of Gardner, Massachusetts. SUMMARY OF THE INVENTION The present invention provides an improved adaptor for coupling a video camera to an endoscope, borescope, or the like. The adaptors of the present invention will generally include a focusing mechanism and an independent "zoom" or magnification variation adjustment mechanism. The zoom mechanism will preferably move two lens assemblies simultaneously, but at different speeds. Each lens assembly preferably includes a pair of lenses affixed together in a doublet. By carefully controlling the position of the doublets relative to a pair of focusing lenses, the present invention can provide an optically compensated zoom mechanism which allows changes in the magnification of the adaptor throughout a wide magnification range without having to refocus the adaptor. The present invention provides a device for coupling a video camera to an endoscope or a borescope for recording and displaying images from within a patient body. The device comprises a clamp to attach the device to the endoscope or borescope. A threaded mount attaches the device to the video camera. A lens system is disposed in an optical path between the clamp and the mount. The lens system includes a focusing and a zoom lens assemblies which are movable along the optical path. The focusing lens assembly relays the image from the attached scope to a fixed position and varies an object distance of the images. The zoom lens assembly further relays the image onto the camera. The focusing lens assembly includes a focusing mechanism and two lens groups. The focusing mechanism moves one lens group relative to the other to relay the images from the attached scope to a fixed position. One of the lens group in the focusing assembly is stationary to keep the system simple. The zoom lens assembly includes a zoom mechanism and two lens groups. The zoom mechanism moves the two lens groups along the optical path so that the images transmitted along the optical path vary in magnification within a zoom range. The zoom mechanism moves the two lens groups in unison so that the images position remains substantially constant when the zoom mechanism varies the magnification throughout the zoom range. Generally, the zoom mechanism will move the lens groups in unison when a zoom actuation handle rotates. This allows for a variable effective focal length (EFL). In one embodiment, the EFL of the device can be varied continuously from about 22.5 mm to about 50 mm. Alternately, in another embodiment, a lens group may be used in the device which allows the EFL to be varied continuously from about 13 mm to about 28 mm. Preferably, each lens group will include a pair of lenses affixed together as a doublet. On the other hand, each lens group of the focusing assembly (which is adjustable independently of the zoom mechanism) may be provided having a single lens. Hence, the present invention can provide a simple zoom adaptor including only six non- planar optical elements with three moving groups. One of the moving groups focusing the images, and the other two moving groups change the magnification without moving the image position. In a first aspect, the present invention provides a device for coupling a video camera to an endoscope or a borescope for recording and displaying images. The device comprises a clamp adapted to attach the device to the endoscope or borescope. A mount is adapted to attach the device to the video camera. A lens system is disposed in an optical path between the clamp and the mount. The lens system includes first and second lens groups which are moveable along the optical path. A zoom mechanism is coupled to the lens groups. The zoom mechanism is adapted to move the first and second lens groups along the optical path so that the images transmitted along the optical path vary in magnification within a zoom range. The zoom mechanism is also adapted so that an image position remains substantially constant when the zoom mechanism varies the magnification throughout the zoom range. In another aspect, the present invention provides an adaptor for coupling a video camera with an endoscope to record images from within a patient body. The adaptor comprises a clamp adapted to attach the adaptor to the endoscope. A mount is adapted to attach the adaptor to the video camera. A focus system includes moveable and fixed focus lenses, and is disposed in an optical path from the clamp to the mount. A focus mechanism is coupled to the moveable focus lens so as to move the moveable lens and vary an object distance of the images. A first lens assembly is disposed in the optical path from the focus system. A second lens assembly is disposed in the optical path from the first lens unit. A zoom mechanism is coupled to the lens assemblies and is adapted to move the lens units along the optical path to vary magnification of the images without varying the object distance. In yet another aspect, the present invention provides an optical imaging device. The device includes a lens system disposed in an optical path. The lens system comprises a first and a second lens group which are movable along the optical path;. The device also comprises a zoom mechanism which is coupled to the lens groups. The zoom mechanism is adapted to move the first and second lens groups along the optical path so that the images transmitted along the optical path vary in magnification within a zoom range. The image position remains substantially constant when the zoom mechanism varies magnification throughout the zoom range. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded side view in partial cross-section showing the structure and use of the adaptor of the present invention for coupling an endoscope to a video camera. Fig. 2 is a cross-sectional side view showing the active optical elements of the zoom adaptor of Fig. 1, and also schematically illustrates a cam-and-follower mechanism for positioning the optical elements to vary magnification without changing an object distance. Fig. 3 illustrates an end view of a clamp for affixing the adaptor of Fig. 1 to an eye piece of an endoscope. Fig. 4 is a partial cross-sectional view of a camera mount of the adaptor of Fig. 1 for coupling the adaptor to a video camera, in which the mount includes a centering mechanism for centering the image, according to the principles of the present invention. DESCRIPTION OF THE SPECIFIC EMBODIMENTS Referring now to Fig. 1, an adaptor 10 couples an endoscope 12 with a video camera 14 so that images normally viewed through an eye piece 16 are directed to the sensor of the camera. Generally, adaptor 10 has an input end 18 and an output end 20. A clamp 22 adjacent input end 18 affixes adaptor 10 to eye piece 16 of endoscope 12. A mount 24 adjacent output end 20 is used to affix the adaptor to the video camera 14. Clamp 22 and mount 24 will preferably accommodate common endoscopic eye piece structures and camera mount receivers, and adaptor 10 will often be available with a variety of clamp and mount structures. To facilitate the use of differing mounts, mount 24 may be affixed to an adaptor body 26 using threads 28, mount 24 often accommodating a V-mount, a bayonet mount, a C-mount, and/or any other proprietary or standard camera mount structure. Clamp 22 will often include a resilient torroidal clamping body 30 which is compressed to affix eye piece 16 to adaptor 10. A wide variety of alternative clamping structures may also be used. In some embodiments, where endoscope 12 is adapted for directly coupling the endoscope to other optical components, clamp 22 may comprise any of the standard or proprietary lens mounting structures described with reference to mount 24, within the scope of the present invention. Adaptor body 26 contains the optical components of the focusing and zoom assemblies of adaptor 10. Focusing is effected by rotation of knob 32, while changes in magnification are effected by rotation of outer tube 34 about the axis 36 of adaptor 10. Adaptor body 26 will generally include a water-tight housing, and the housing and optical components therein will be adapted to withstand cold-soak sterilization. The optical elements and actuation mechanisms of adaptor 10 are illustrated more clearly in Fig. 2. Beginning at input end 18, light rays from the endoscope will enter adaptor body 26 through a planar glass window 36. The light rays are first diverging using a focus assembly 38 to form a virtual image. The virtual image is then directed through first and second lens groups 40, 42 before exiting adaptor 10 through an output planar window 44. First and second lens groups 40, 42, together with a zoom mechanism 46, define an optically compensated zoom system which focuses the light rays from the focus assembly to provide a variable magnification image on the CCD sensor of the video camera. In one embodiment, focusing assembly 38 includes a moveable lens 48 and a fixed lens 50. These lenses will preferably comprise positively and negatively powered lenses, respectively. Moveable lens 48 will ideally have an effective focal length of 16.93 mm, while fixed lens 50 will have an effective focal length of -10.58 mm. Moveable lens 48 is moved by rotating focus adjustment 32 having an eccentric pin, as illustrated. First lens group 40 includes a pair of lenses 40a, 40b which are cemented together to form a doublet 40c. Similarly, second lens group 42 includes first and second lenses 42a, 42b which are cemented together to define a doublet 42c. In the exemplary embodiment, first doublet 40c has an effective focal length of 39.15 mm, while second doublet 42c has an effective focal length of 50.42 mm. These two doublets move in unison as guided by zoom mechanism 46. Zoom mechanism 46 makes use of pins 52 which extend from each of the zoom lens assemblies. More specifically, pin 52 extending from first doublet assembly 40 rides in a first slot 54, while the pin extending from the second doublet assembly 42 rides in a second slot 56. Slots 54 and 56 extend roughly helically about adaptor body 26, and rotate about the axis of the adaptor with outer tube 34. Planar projections of the slots are illustrated as first planar slot 54a and second planar slot 56a in Fig. 2. An axial slot 58 restrains the radial position of pins 52 when outer tube 34 rotates, so that first and second doublet assemblies 40, 42 move axially within the lens body in precise relationship. When the distance between the two doublet assemblies 40, 42 is changed, the EFL of the zoom assembly 26 varies. With the above described optics, the EFL variation can range from between about 22.5 mm to about 50 mm, which is ideal for use with a V--" CCD video camera sensor. This change in EFL results in an image magnification change. The common motion of the two doublet assemblies compensate for the change in position. As a result, the image remains in a constant focal plane when the magnification changes. O-rings 60 disposed between the individual housing and adjustment components of adaptor body 26 ensure that the adaptor is sufficiently watertight to withstand cold-soak sterilization. In yet another embodiment, adaptor 10 includes the same components as described above and illustrated in Fig. 2. However, in this embodiment, moveable lens 48 will alternatively have an effective focal length of -21.33 mm, while fixed lens 50 will have an effective focal length of 192.45 mm. As before, the components of adaptor 10 will function together as heretofore described to provide the image in a constant focal plane when the magnification changes. In this embodiment, first lens group 40, which includes the pair of lenses 40a, 40b, which are cemented together to form doublet 40c, has an effective focal length of 26.86 mm. Similarly, second lens group 42, which includes first and second lenses 42a, 42b, which are cemented together to define doublet 42c, has an effective focal length of 34.84 mm. As the two doublets move in unison, guided by zoom mechanism 46, the EFL can be varied ideally from about 13 mm to about 28 mm. This range is ideal for use with video cameras having 1/3" and V" CCD sensors. Referring now to Fig. 3, a series of vents 62 allow air to flow from the surrounding environment to the space between input window 36 and eye piece 16, thereby minimizing fogging of the eye piece during use. Referring now to Fig. 4, camera mount 24 will preferably include horizontal adjustment screws 64 for centering of the image. Rotation of adjustment screw 64 will translate adaptor body 26 laterally relative to the video camera. Typically, two orthogonal alignment screws will be provided about the axis 36 of the adaptor to adjust the location of the image on the video screen both vertically and horizontally. When using adaptor 10 for imaging the internal tissues of a patient body, endoscope 12 may optionally be positioned prior to attaching the adaptor to the scope. Alternatively, the endoscope, adaptor, and video camera may be affixed together during positioning of the scope. Regardless, adaptor 10 will be affixed to eye piece 16 of scope 12 by compressing clamping body 30, generally using a quick-release clamp actuator. Mount 24 will often be selected from among a variety of mount structures so as to be suitable for the mount receiver of video camera 14. Mount 24 will then be affixed to adaptor body 26 using threads 28. Once the mount is attached to video camera 14 and the clamp is affixed to eye piece 16 of endoscope 12, adaptor 10 is ready to transmit images from the endoscope to the camera. Prior to focusing the image, outer tube 34 is rotated to move the first and second lens assemblies to a position providing a high degree of magnification. This helps to ensure that the focus is sufficiently accurate throughout the magnification range. Next, focus adjustment 32 is rotated until the image provided through video camera 14 is sharp and clear. Preferably, the focus system will be capable of adjusting for object distances measured from the adaptor, throughout the range of from about 10 inches to about 20 inches, and ideally from about 10 inches to infinity. Once endoscope 12 is positioned and the focus system has been adjusted, tissues which remain at a fixed distance from the distal end of scope 12 will remain in focus while the zoom control mechanism varies the magnification provided through adaptor 10 throughout the zoom range. Therefore, the physician is free to adjust the degree of magnification as required, and need not refocus the adaptor after each change in magnification. Tissues will also remain in focus during changes in magnification. To effect changes in magnification, outer tube 34 is rotated about the axis 36 of adaptor 10. Rotation of outer tube 34 can allow the surgeon to move from a low magnification and a wide field of view, such as during introduction of laparoscopic instruments to the surgical site, to an increased magnification giving view of greater detail. Throughout these changes, focus need not be adjusted, thereby allowing the surgeon to view the tissues without interruption substantially throughout the procedure. If endoscope 12 is repositioned, or if the tissues are moved relative to the distal end of the scope, refocusing can easily be provided by adjusting the focusing system. While exemplary embodiments have been described in some detail, for purposes of clarity of understanding and by way of example, a variety of changes, modifications, and adaptations will be obvious to those who skill in the art. For example, by changing the EFL of the lenses provided for use in the doublets described above, a variety of zoom ranges may be realized. Thus, as the need arises for greater magnification capabilities and as camera sensors continue to be made smaller, the EFL will continue to be reduced or enlarged as necessary. Therefore, the scope of the present invention is limited solely by the appended claims.

Claims: WHAT IS CLAIMED IS: L A device for coupling a video camera to an endoscope or borescope for recording and displaying images, the device comprising: a clamp adapted to attach the device to the endoscope or borescope; a mount adapted to attach the device to the video camera; a lens system disposed in an optical path between the clamp and the mount, the lens system comprising first and second lens groups which are movable along the optical path; and a zoom mechanism coupled to the lens groups, the zoom mechanism adapted to move the first and second lens groups along the optical path so that the images transmitted along the optical path vary in magnification within a zoom range, and so that an image position remains substantially constant when the zoom mechanism varies magnification throughout the zoom range. 2. The device of claim 1 , wherein the zoom mechanism moves the lens groups relative to each other when a zoom actuation handle moves so as to vary the magnification and the common motion of the lens groups while keeping the image position constant. 3. The device of claim 2, wherein the zoom range extends from an effective focal length (EFL) of about 22.5 mm to about 50 mm. 4. The device of claim 2, wherein the zoom range extends from an effective focal length (EFL) of about 13 mm to about 28 mm. 5. The device of claim 2, wherein the lens system further comprises a movable focus lens, and further comprising a focus mechanism which moves the movable focus lens along the optical path to vary the object, the focus mechanism being movable independently of the magnification of the images. 6. The device of claim 5, wherein the lens system further comprises a fixed focus lens. 7. The device of claim 6, wherein the focus lenses can focus the images throughout an object distance range from at least about 10 inches to infinity. 8. A device as claimed in claim 6, wherein the first and second lens groups comprise first and second doublets in the optical path from the focus lenses, each doublet including a pair of lenses attached together, and wherein the zoom mechanism moves the first and second doublets so that the doublets vary the magnification without varying the image position. 9. A device as claimed in claim 6, wherein the movable focus lens comprises a positive lens with an effective focal length of about 16.93 mm, wherein the fixed focus lens comprises a negative lens with an effective focal length of about -10.58 mm, wherein the first doublet has an effective focal length of about 39.15 mm, and wherein the second doublet has an effective focal length of about 50.42 mm. 10. A device as claimed in claim 6, wherein the movable focus lens comprises a negative lens with an effective focal length of about -21.33 mm, wherein the fixed focus lens comprises a positive lens with an effective focal length of about 192.45 mm, wherein the first doublet has an effective focal length of about 26.86 mm, and wherein the second doublet has an effective focal length of about 34.84 mm. 11. A device as claimed in claim 1 , further comprising a centering mechanism coupled to at least one of the mount and the clamp, the centering mechanism adapted to displace the optical path laterally to center the image to the CCD sensor. 12. An adaptor for coupling a video camera with an endoscope to record images from within a patient body, the adaptor comprising: a clamp adapted to attach the adaptor to the endoscope; a mount adapted to attach the adaptor to the video camera; a focus system including movable and fixed focus lenses disposed in an optical path from the clamp to the mount, and a focus mechanism coupled to the movable focus lens so as to move the movable lens to vary an object distance of the images; a first lens assembly disposed in the optical path from the focus system; a second lens assembly disposed in the optical path from the first lens unit; and a zoom mechanism coupled to the lens assemblies and adapted to move the lens units along the optical path to vary magnification of the images without varying the object distance. 13. An adapted as claimed in claim 12, wherein the lens assemblies comprise doublets, each doublet including first and second lenses attached together. 14. An adaptor as claimed in claim 12, wherein the zoom mechanism comprises a tubular body disposed about the optical path, the body having first and second slots, a first pin coupled to the first assemblies unit and engaging the first slot so that the first slot repositions the first lens assembly when the body rotates, and a second pin coupled to the second lens assembly and engaging the second slot so that the second slot repositions the second lens assembly when the body rotates. 15. An adaptor as claimed in claim 12, further comprising a centering mechanism coupled to at least one of the mount and the clamp, the centering mechanism adapted to displace the optical path laterally to center the image. 16. An adaptor as claimed in claim 13, wherein the optical path between the clamp and the mount is substantially composed of the doublets of the first and second lens assemblies, the fixed and movable lenses of the focus system, and one or more planar lenses. 17. An adaptor as claimed in claim 12, wherein the optical path between the path and the mount includes no more than 6 non-planar lenses. 18. An optical imaging device comprising: a lens system disposed in an optical path, the lens system comprising first and second lens groups which are movable along the optical path; and a zoom mechanism coupled to the lens groups, the zoom mechanism adapted to move the first and second lens groups along the optical path so that the images transmitted along the optical path vary in magnification within a zoom range; wherein an image position remains substantially constant when the zoom mechanism varies magnification throughout the zoom range. 19. A device as claimed in claim 18, wherein the lens system further comprises: a movable focus lens; and a focus mechanism which moves the movable focus lens along the optical path to vary the object, the focus mechanism being movable independently of the magnification of the images, wherein the first and second lens groups comprise first and second doublets, each doublet including a pair of lenses, and wherein the zoom mechanism moves the first and second doublets so that the doublets vary the magnification without varying the image position. 20. A device as claimed in claim 19, wherein the zoom mechanism moves the lens groups relative to each other when a zoom actuation handle moves to vary the magnification and the common motion of the lens groups while keeping the image position constant.

Inventors: HOWES ALLEN R, LI SHIFANG, HOWES, ALLEN, R., LI, SHIFANG
Applicants: TRANSAMERICAN TECHNOLOGIES INT, TRANSAMERICAN TECHNOLOGIES INTERNATIONAL DOING BUSINESS AS TTI MEDICAL
Application year: 1998
Main classification: G02B15
IPC codes: G02B23