Abstract:
A fiber optic endoscope which uses a bundle of coherent fiber to convey both an optical image in one direction and illumination light in the other direction. A fraction of the optical fibers are used for the illumination, and others of the fibers are used for the image. Notched fibers can be used for the illumination.

Description:
This is a continuation of application Ser. No. 08/890,803 filed on Jul. 11, 1997, now U.S. Pat. No. 6,013,025. This application claims benefit to provisional application 60/022,023 filed on Jul. 11, 1996. 
    
    
     FIELD OF THE INVENTION 
     The present application describes an integrated illumination and imaging system. In one form, these concepts are particularly adapted for use with an endoscope which has the capacity to illuminate a site of investigation and transmit an image of that site by an-image carrying transmission medium. 
     BACKGROUND OF THE INVENTION 
     Micro invasive surgery has a goal of minimizing the amount of damage caused during surgery. Some surgical procedures, for example, can be obviated by using an endoscope through a small incision. The size of the incision, therefore, depends on the size of the endoscope. One important feature of an endoscope, therefore, is its size. Since many endoscopes require a separate light guide, this increases the size of the endoscope. 
     Current endoscopes often use some type of illumination bundles or light guides to couple light to a site of viewing. The site of viewing is then imaged by appropriate receiving of the coupled light that is reflected by the area of the viewing site. 
     The present application describes a system that eliminates the need for a separate light guide and thereby reduces the requisite, probe dimensions for a desired image size. Like current endoscopes, endoscopes using this new technique are safe to introduce into the human body for use in minimally invasive surgery. One application of this device is in the area of root canal procedures in dentistry, although this system could similarly be used in other kinds of surgery. 
     International Patent Application No. WO 91/15793, by Acosta, et al., discloses an endoscope in which light is transmitted to and from an anatomical site. One embodiment of the Acosta, et al. endoscope includes a plastic optical fiber assembly in which light is transmitted to the distal end of the endoscope along the periphery of the fiber assembly itself. Imaging light is transmitted back to the proximal end through a central multi-fiber bundle. 
     Another embodiment of the Acosta, et al. application discloses a plastic optical fiber assembly in which illuminating light is directed through a predetermined portion of the multi-fiber bundle. The balance of the bundle is.dedicated to transmitting imaging light. 
     An alternative embodiment of the Acosta, et al. Application described an endoscope in which a beam splitter directs light across the entire face of the multi-fiber bundle. The returning imaging light is also transmitted through the entire crosssectional area of the bundle through the beam splitter to a viewing portion of the endoscope, which is proximal to the beam splitter. 
     SUMMARY OF THE INVENTION 
     The inventors recognized a need for an illumination and imaging device which does not require a predetermined subset of fibers to be dedicated to transmitting either illuminating or imaging light. There is a further need for a self-filtering illumination and imaging device in which variable and dynamically changing portions of the multi-fiber bundle transmit either illuminating or imaging light. 
     An illuminating and imaging system of this system enables alternate functions of illuminating and imaging transmissions to be separately applied to non-dedicated, dynamically alterable subsets of the multi-fiber image bundle; 
     will function using any type of image carrying transmission medium with partitioned or pixeled capability; 
     enables all fibers of a multi-fiber image bundle to serve in either illumination or image transmission; 
     needs no separator or additional cladding between fiber portions of the image bundle; 
     non-simultaneously uses all portions of a fiber optic bundle for both illumination and image transmission; and 
     functions as a self-filtering system due to the placement of the light emitting element with respect to the fibers which are transmitting illuminating light, thereby eliminating a sensation of glare when the image is viewed or recorded. 
     Main advantages to this system over those proposed previously include: 
     1. Removal of light guides to make the bundles smaller and therefore less invasive; 
     2. Reduction of the complexity of a given endoscope, which reduces the difficulty and the cost of its manufacture; and 
     3. Removal of the light guides allows the entirety of an endoscope&#39;s cross sectional area to be devoted to the image bundle. Therefore, an endoscope operating by means of this proposed system can produce a higher resolution image than conventional endoscopes of equal cross-sectional area. 
     We have considered multiple methods of implementing this dual function bundle. They include the following: 
     1. Stationary Light Channeling 
     Channeling Above Bundle 
     2. Stationary Light Channeling 
     Channeling Within Bundle 
     3. Oscillating Light Channeling 
     4. Rotary Light Channeling 
     Rotation on Axis with Bundle 
     Light Sources Stationary 
     5. Rotary Light Channeling 
     Rotation on Axis with Bundle 
     Light Sources Rotate with Channeling Devices 
     6. Rotary Light Channeling 
     Rotation on a Parallel Axis with Bundle Axis 
     Light Sources Stationary 
     7. Cantilever Beam 
     Bending within the illumination plane 
     Light Source(s) Stationary 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the invention will be described with reference to the accompanying drawings, wherein: 
     FIG. 1 shows a general drawing of the endoscopic device; 
     FIGS. 2A and 2B show a first embodiment operating to channel the light above the bundle; 
     FIGS. 3A and 3B shows a device which channels with the bundle; 
     FIG. 4 shows an endoscope with an image bundle that alternates functions between illumination and image transmission; 
     FIG. 5 shows a system rotating on axis with the bundle; 
     FIG. 6 shows an embodiment with additional light sources that rotate; 
     FIG. 7 shows an embodiment operating to rotate on a parallel axis to the bundle axis; 
     FIG. 8 shows a Cantalever beam system; 
     FIG. 9 shows an endoscope with prisms; 
     FIGS. 10-A,  10 -B and  10 -C shows an endoscope with prismatic chopping wheels; 
     FIGS. 11-A,  11 -B and  11 -C shows an endoscope with fiber optic guide; 
     FIG. 12 shows a Cantalever beam with fiber like channels; 
     FIG. 13 shows a fiber light conductor mounted to the beam. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An endoscope  30  of the preferred embodiment is depicted in FIG. 1 as imaging an anatomical site  32  whose image is desired to be detected. The system operates by discretely projecting radiation, e.g., light, through a portion of a light transmission device. The preferred embodiment uses the fibers  42  in the image bundle  44  of a fiber optic endoscope  30 . This system operates to remove thel necessity of separate light guides for illumination. The outer surface of the image bundle represents the hole size that needs to be made in order to insert the endoscope device. 
     A light illuminating device is effected by gathering light from external light source  34  by light focusing device  36 , and coupling that light into light channeling device  38 . Light is then focused on a specific location or locations of image bundle  42  of endoscope  30  at its proximal end  44 . Light focusing from light channeling device  38  may be incorporated directly into image bundle  42 , or may be accomplished by a gradient index (GRIN) lens  46  mounted to the proximal end  44  of fiber optic bundle  44 . The exposed portions of the bundle then carry light from the proximal end to distal end  48  of endoscope  30 , where the accumulated light then illuminates the site of interest  32 . The remainder  50  of bundle  42  having its fibers unexposed to light at the proximal end, collect light reflected from the surfaces in the site of interest and carry it to proximal end  44  of endoscope  30 . That light is then magnified by camera optics  52  and collected by recording device  54 , such as a digital video camera. 
     Embodiment 1. Stationary Light Channeling 
     This first embodiment is shown in FIGS. 2A and 2B, and uses the operation of channeling above bundle. 
     Endoscope  30  includes light channeler  38  permanently mounted above the portion of the GRIN  46  or the image bundle. Light channeler is dedicated to illumination. Light from external source  34  is focused by focusing device  36  and aimed at light channeler  38 , which then transmits this light onto the portion  56  of the bundle over which it is located. In this version of the device, section  56  of the image bundle located below the channeler  38  is permanently dedicated to illumination. The image receiving device records an image proximate distal end  48  of bundle  42  partially obscured by light channeler  38 . 
     Embodiment 2. 
     The second embodiment uses stationary light channeling, and is shown in FIGS. 3A and 3B. This operates to carry out channeling with the bundle. 
     Endoscope  60  includes channeling device  61  integrated within the bundle. Channeler  61  is formed by notch  62  cut into outside wall  64  of bundle  66 . Notch  62  has the proper geometry to receive light from direct light source  34  and divert the light toward the distal end of bundle  66 . Light received from notch  62  travels through bundle  66 . This system uses the exposed fibers  68  as being permanently dedicated to illumination. FIG. 3B shows that light channeling may be accomplished by one or more notches  62  placed in bundle wall  64 , which expose one or more sets of fibers  68  to illuminating light. 
     Embodiments 1 and 2 differ from current endoscope technology by eliminating the need for light guides for illumination. This is done by permanently dedicating a section of the image bundle fibers to serve the function of illuminating the sight of examination at the distal end of endoscope. 
     The remaining embodiments, unlike embodiments 1 and 2, use light channeling devices are in motion with respect to the fiber optic bundle they are illuminating, and the device used to record the image (the camera). The channelers at a given instant in time obscure the bundle from view as do those in embodiment 1, yet the portion they obscure is not the same over time. The motion of the channeler(s) is fast enough that the recorded image appears like an image seen through a propeller or ventilation fan in motion. 
     At any given moment, the portion of the image bundle exposed to the light channeling device may range from 100% to 0%. Equivalently, at any given moment, the portion of the image bundle exposed to the optical recording device may range from 0% to 100%, but in practice will be less than the full range of the multiplexed use of the device, the optical range between about 30% and 70%. 
     As will be appreciated, the oscillation or rotation rates of the remaining embodiments lie within the range of the sampling rate of the detector. 
     Embodiment 3. Oscillatory Light Channeling 
     Endoscope  80  shown in FIG. 4 differs from embodiments 1 and 2 in that sections of GRIN lens  46 , hence image bundle  42 , alternate functions between illumination and image transmission. One or more light channelers  82  oscillate as shown by arrow  84 . At a given instant, whatever portion of the bundle is located directly below the light channeler transmits light to a site of interest for illumination, while at other times the same portion provides image transmission. As with embodiments 1 and 2, the channeler receives light from a fixed external light source. 
     Embodiment 4. Rotary Light Channeling 
     This embodiment is shown in FIG.  5 . The system described operates to carry out rotation on Axis with Bundle, and using stationary light Sources. 
     Endoscope  90  employs one or more reflectors (or channelers)  92  rotating about the bundle axis  94  as shown by arrow  96 . Rotation of reflectors  92  in this manner provides for illumination to different sections of GRIN lens  46 , hence image bundle  42  (not shown), at different times. In this embodiment, light is provided by one or more fixed external sources appropriately aimed and focused onto the reflectors  92 . 
     Embodiment 5. Rotary Light Channeling 
     FIG. 6 shows this embodiment using rotation on Axis with Bundle, and light Sources Rotate with Channeling Devices. 
     In endoscope  100 , one or more light sources  102  are dedicated to channelers  106 . That is, these endoscopes rotate as depicted by arrows  108  along with channelers  106  over GRIN lens  46 , hence bundle  42 , out of the range of view of the image recording device (not shown). 
     Embodiment 6. Rotary Light Channeling 
     FIG. 7 shows this embodiment using Rotation on a Parallel Axis with Bundle Axis, with stationary light Sources Stationary endoscope  120  includes channelers  122  which rotate about axis  124  which is parallel to axis  126  of image bundle  42 , yet offset by some fixed distance  128 . Illumination plane  130  is located some fixed distance above image bundle  42  and a fixed distance below the image recording device (not shown). A single light source  132 , located at a predetermined location within illumination plane  130 , is aimed at image bundle axis  126 . As a channeler  122  passes over image bundle  42  in its orbital travel  134 , channeler  122  collects light from the source  132  and directs the light onto portion  136  of bundle  42  over which channeler  122  is traveling. 
     Embodiment 7. The Cantilever Beam 
     The concept of the cantilever beam, which bends with the illumination plane using a stationary light Source, is shown in FIG.  8 . 
     Endoscope  140  uses a cantilever light beam  142  which extends from light source  144 . Beam  142  cyclically deflects light from its neutral axis  146  into proximal end  44  of image bundle  42 . The path of deflection  150  exists within illumination plane  152  and intersects with bundle axis  148  between proximal end  44  of image bundle  42  and recording device  54 . Beam  142  acts as a carrier for a light channeler located at the bundle axis (not shown) or may serve as a light channeler itself. Light source  144 , located at the fixed end of beam  142 , is aimed at the light channeler if a light channeler is present. An illumination path originates at light source  144 , travels along or through beam  142  to the light channeler, and enters the section of the bundle  42  directly below the channeler. As the beam bends back and forth over proximal end  44  of image bundle  42 , different portions of image bundle  42  are exposed to the channeler at different points in time. Like embodiments 3-6, this arrangement provides the opportunity for portions of the image bundle to function at one instant in time as an element which illuminates light transmission from the proximal to distal end of the bundle and as a device for imaging light transmission from the distal end to the proximal end of the bundle, at another instant in time. Beam oscillation is accomplished by means of a driver, or actuator  154 , or by the beam  142 , itself, depending on the actuation implementation chosen. 
     Actuators for oscillatory motion include, but are not limited to, slider-crank mechanisms, piezoelectric vibratory actuators, self-actuating cantilever light beams, and exploitation of intermittent magnetic or electric fields. For rotary motion, actuators include but are not limited to direct drive rotary motors, gear transmissions driven from rotary motors, servo motors, and air drive systems generated either from a fan or from natural convection currents generated from the light source. 
     Light channelers include but are not limited to the following devices: prisms, fiber optic light guides, transparent disks in which are machined facets which function as prisms, transparent disks on which are discreetly placed patches of refractive film causing light traveling through the disk to divert out of the disk in the desired direction. 
     The following embodiment descriptions are examples of how certain light channelers could be implemented. Implementations of these light channelers are not limited to the embodiments illustrated below. 
     Oscillatory Motion With Prismatic Channeler (See FIG. 9-1) 
     In endoscope  160 , one or two prisms  162  oscillate within illumination plane  163  diverting light originating from source  165  from illumination plane  164  into image bundle  42 . As shown, illumination plane  164  is normal to bundle axis  166  and coincident with light source  165  and prisms  162 . 
     Prismatic Chopler Wheel (See FIGS. 10-1,  10 - 2 ,  10 - 3 ) 
     VERSION 1: In endoscope  170  light is channeled via transparent disk  172  spinning about axis  188 , parallel to illumination axis  174  within illumination plane  176 . Slightly below outer rim  178  of disk  172  at opposite points across illumination axis  174  are located exiting face  180  of fixed light source  182  and proximal end  44  of imaging bundle  42 . 
     In outer rim  178  of transparent disk  172  are cut a plurality of prismatic protrusions  184 . When aligned over light source  182 , prismatic protrusions  184  divert light from source  182  into illumination plane  176 . Disk  172  rotates in illumination plane  176 . When located above image bundle  42 , prismatic protrusions  184  channel light out of illumination plane  176  and into image bundle  42 . Disk  172  allows light transmission between the point at which it is received from light source  182  to its target on image bundle  42 . Transparent disk  172  rotates in direction  186  about axis  188  in illumination plane  176 . 
     The image transmitted from image bundle  42  through the spaces not occupied by the protrusions may be viewed or recorded by recording device  54 . The viewed image is similar to that seen looking through a rotary fan or a propeller. 
     VERSION 2: In endoscope  190  (FIG.  10 - 3 ), transparent disk  192  is identical to transparent disk  172  except that its center has been removed to allow clearance space  194  for light source  196 . As in the case of endoscope  170 , transparent disk  192  spins within illumination plane  198  about illumination axis  200 . Light enters image bundle  42  through the same means of prismatic protrusions (not shown). located at rim  202  of transparent disk  192 . What differs in this version is the location of light source  196 . Light source  196  is located within illumination plane  198  at the illumination axis  200 , i.e., in the center hole  194  at the center of the disk described above. Light source  196  is aimed directly at bundle axis  204 . Light is transmitted from the center of the disk to the disk&#39;s rim  202  where is then diverted into GRIN lens  46 , thence into image bundle  42 , by-means of the channeling protrusions (not shown). 
     Fiber Light Channels Mounted to a Wheel (See Drawings  11 - 1 ,  11 - 2 ,  11 - 3 ) 
     Endoscope  210  is similar to endoscopes  160  and  170  described above with the following differences. In the place of prismatic protrusions  184 , a plurality of fiber optic light guides  212  are positioned over transparent disk  214 . At a given instant, when one end  216  of one of fiber optic guides  212  is located over image bundle  42 , the other end  218  of fiber optic guide  212  is located above light source  182 . In this case then, the actual light channeler is light guide  212 . Transparent disk  214  acts as a carrier of the light guides, and means to precisely position them. In this embodiment, recording device  54  receives the image from bundle  42  through transparent disk  214  between fiber optic guides  212 . 
     Fiber Light Channelers Mounted to Beam (See Drawing  12 - 1 ) 
     In endoscope  230  light channeling consists of fiber optic light guide  232  partially embedded within cantilever beam  234 . Cantilever beam  234  oscillates within illumination plane  235  about image bundle axis  166 . Light may be focused from light source  236  into light guide  232  by means of a light focusing device  238 , such as converging lens(es). Light then travels through light guide  232 , which is mounted to oscillating beam  234 , to a light channeler  240 , such as prism. Channeler  240  is located in illumination plane  235  at bundle axis  166 . Light entering channeler  240  from light guide  232  is diverted into image bundle  42 . In endoscope  230 , light may enter directly into imaging bundle  42  from the channeler instead of entering a GRIN lens (not shown). If a GRIN lens is employed the light may be further focused before entering the image bundle. Beam oscillation is accomplished by means of beam driver or actuator  242 . 
     Fiber Light Conductor Mounted to Beam (See Drawing  13 ) 
     Endoscope  250  is a further variation of the embodiment depicted by endoscope  230 . Except for the details contained herein, it will be appreciated that other elements not depicted are the same. In endoscope  250 , distal portions  252  of at least one fiber optic guide  254  are embedded within a distal portion  256  of beam  258 . Axes  260  of portions  252  are parallel with respect to each other. Beam  258  is disposes so that axes  260  extend into image bundle  42  and such that axes  260  are parallel to axis  148  of image bundle  42 . Proximal ends  262  of fiber optic guides open toward light source  34 . Light from light source  34  may be focused by light focusing device  36 . In use, distal portion  256  oscillates as shown by arrow  264  generally perpendicular to axis  148 , thereby directing light over a variable portion of image bundle  42 . 
     FABRICATION 
     Fabrication techniques employed in producing above devices include but are not limited to conventional large scale fabrication techniques, such as milling, turning, molding, etc. Also less conventional means of fabrication may be employed such as surface micro-machining, and other techniques exploited in the production of microelectromechanical systems (MEMS). 
     Other embodiments are within the following claims. For example, any device which receives light from a light source and channels it into a discrete portion of the image bundle could be used as the light channeler. 
     It will be appreciated that the GRIN lens is used primarily for magnification, and may or may not be present with any particular embodiment in which there is a need or desire for magnification. 
     While the preferred embodiment describes using light to illuminate the area to be imaged, it should be understood that other forms of energy, including, for example, UV, IR and ultrasound, could be used for this imaging.