Image relaying device and image detecting device

An image relaying device comprises a shaft, an objective lens at a distal end of the shaft, an optically transparent window region in a proximal end region of the image relaying device, an optical system in the shaft, the optical system relaying an image produced by the objective lens to the proximal end region in a way that the relayed image can be captured through the window region. The optical system's optical axis at the window region is orthogonal or substantially orthogonal to the optical system's optical axis in the shaft. An optical instrument makes use of a plurality of these image relaying devices and a corresponding plurality of image sensors where the optical path length of each image relaying device may be independently adjusted to correct for optical inconsistencies in the elements of each relaying device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Application No. 102017105354.9 filed Mar. 14, 2017, incorporated herein by reference.

FIELD OF THE INVENTION

The present invention refers to an endoscope, an exoscope or another image relaying device and to an image detecting device detecting or sensing or capturing an image relayed by an image relaying device. The invention further concerns devices configured to relay or detect stereo images comprising at least a first image to be provided to a left eye of a user and a second image to be provided to a right eye of the user, thereby producing a three-dimensional impression.

BACKGROUND OF THE INVENTION

An exoscope is an image relaying device configured for being positioned and used outside a human or animal body. Like a surgical microscope, or operating microscope, an exoscope is generally used for imaging of objects at or close to the surface of the body and visible from outside. In many cases, an exoscope is smaller than a surgical microscope. In many cases, an exoscope is generally used for a larger object distance than a surgical microscope is. Unlike an endoscope, an exoscope may not be adapted for being inserted, through a natural or artificial orifice, into a cavity but is configured to operate outside the body. A borescope is similar to an endoscope but generally adapted for technical applications rather than for medical applications.

Conventional stereoscopic endoscopes or exoscopes comprise two objective lenses and two image sensors at their distal ends. Other stereo endoscopes or stereo exoscopes comprise two objectives at their distal ends, two image relaying systems relaying images produced by the objective lenses to their proximal end, and two image sensors at their proximal end. Other conventional stereo endoscopes comprise two objective lenses at their distal end, two image relaying systems relaying images produced by the objective lenses to their proximal end, and two parallel interfaces at their proximal end allowing a mechanical and optical coupling of a stereo camera with two image sensors to the proximal end of the stereo endoscope.

For many applications, there are good reasons not to integrate image sensors into an endoscope or into an exoscopes, in particular regarding costs of manufacture and repair, adaptability to different applications with different hardware requirements, and sterilization. When the image sensing or image detecting device is separable from the image relaying device, the interface between both devices and the compensation of variations within the manufacturing tolerance provides particular challenges.

An object of the present invention is to provide an improved endoscope or exoscope or other image relaying device and an improved image detecting device, in particular facilitating compensation for variations of characteristics of components and providing a high quality interface between both devices.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention concern themselves in part with providing an interface between an image relaying device and an image detecting device that is, compared to conventional devices, rotated by a given angle, for example, 90 degrees. Light from an object to be observed or imaged travels parallel to a shaft of the image relaying device, is reflected in a proximal end region of the device, and passes a window travelling in a direction orthogonal to the longitudinal axis of the shaft. A window in a proximal end region of the image relaying device through which the light leaves the image relaying device and a window of the image detecting device through which the light enters the image detecting device can be parallel to each other and also parallel to the longitudinal axis of the shaft of the image relaying device.

An image relaying device comprises a shaft, an objective lens at a distal end of the shaft, an optically transparent window region in a proximal end region of the image relaying device, and an optical system in the shaft. The optical system relays an image produced by the objective lens to the proximal end region such that the relayed image can be captured through the window region, wherein the optical system's optical axis at the window region is orthogonal or substantially orthogonal to the optical system's optical axis in the shaft.

The image relaying device may be an endoscope, borescope or an exoscope for medical or technical applications. The shaft can be rigid and straight or curved, or flexible. The objective lens at the distal end of the shaft can be configured for a direction of view parallel to the longitudinal axis of a shaft or for any other predetermined constant or variable direction of view.

The optically transparent window region is, in particular, at least a part of an opening of a casing, or housing of the image relaying device. This opening is, in general, hermetically closed by an optically transparent window element made of glass, sapphire or any other optically transparent material. The proximal end region of the image relaying device can be a proximal end region of the shaft. As an alternative, the proximal end region of the image relaying device can have a cross section different from, and, in particular, larger than the cross section of the shaft.

In case of a rigid and straight shaft, the optical system comprises, for example, a series of rod lenses or other relay lens units wherein each relay lens unit produces, from a first real intermediate image distal to the relay lens unit, a second real intermediate image proximal to the relay lens unit. The most proximal real intermediate image can be orthogonal or parallel to the optical system's optical axis in the shaft. The optical system can be configured to produce, from the most proximal real intermediate image, a virtual image which can be captured by a camera. As an alternative, the optical system can be configured to produce a real image outside, or downstream from, the optically transparent window region at a place where the image sensor of an image detecting device can be placed. The optical system's optical axis at the window region can be orthogonal or substantially orthogonal or, as an alternative, not parallel to the optical system's optical axis in the shaft.

In an image relaying device as described herein, the optical system can comprise a reflecting interface bending the optical system's optical axis. The reflecting interface can be a surface of a mirror (i.e. an interface between air or another gas or vacuum or glass and a thin metal layer). As an alternative, the reflecting interface can be a surface of a prism or an interface between two prisms made of materials with different refractive indices, wherein total internal reflection occurs at the interface. The angles between the reflecting interface and each arm of the optical system's optical axis are, in general, 45 degrees. The reflecting interface is, in general, arranged between the proximal end of the most proximal rod lens or other relay unit and the optically transparent window region. In general, no light refracting element is situated between the reflecting interface and the optically transparent window region.

An image relaying device as described herein can further comprise an adjustment mechanism facilitating adjustment of the position of the reflecting interface. The adjustment mechanism generally facilitates adjustment of the position of the reflecting interface at or near the end of manufacture or during maintenance or repair of the image relaying device or at some other time post manufacture. After adjustment of the adjustment mechanism, the adjustment mechanism can be sealed or blocked as a final or near-final step of manufacture or maintenance or repair. The adjustment mechanism generally supports the reflecting interface (i.e. the mirror or prism comprising the reflecting interface). For example, the adjustment mechanism may comprise a sliding carriage which can be moved in one direction along a rail or another structure. The adjustment mechanism may also comprise a screw wherein a rotation of the screw causes a displacement of the reflecting interface.

Characteristics of rod lenses or other components of the optical system are dispersed within a non-punctiform region of manufacturing tolerance, or engineering tolerance. As a consequence of dispersion of characteristics, the position of the most proximal real intermediate image rarely corresponds exactly to the original design. The ability to apply an adjustment to the position of the reflecting interface allows for a compensation of the position of the most proximal image produced by the optical system. In this way, the position of the most proximal (real or virtual) image produced by the optical system of an image relaying device can be adjusted precisely to an optimum design position. With this adjustment or compensation, the image relaying device provides an improved interface to an image detecting device.

In an image relaying device as described herein, the adjustment mechanism can facilitate translational displacement of the reflecting interface in a direction not parallel to the reflecting interface.

In an image relaying device as described herein, the adjustment mechanism can facilitate translational displacement of the reflecting interface in a direction parallel to the longitudinal axis of the shaft.

In an image relaying device as described herein, the adjustment mechanism can facilitate translational displacement of the reflecting interface in a direction parallel to the optical system's optical axis in the shaft or at the window region.

Translational displacement of the reflecting interface in a direction not parallel to the reflecting interface alters the length of the optical path from the objective lens along the optical system to the window region. A translational displacement of the reflecting interface in a direction parallel to the longitudinal axis of the shaft can be achieved with a sliding carriage moving along any kind of rail parallel to the shaft. A translational displacement of the reflecting interface in any other predetermined direction can be achieved with a sliding carriage moving along any kind of rail parallel to this predetermined direction.

An image relaying device as described herein can comprise a position indicator providing information comprising the position of the reflecting interface to a receiver outside the image relaying device. This position indicator can comprise a magnet at the adjustment mechanism. The magnetic field produced by the magnet can be sensed or detected outside the casing of the image relaying device. In particular, a Hall effect sensor (Hall sensor) or another sensor or detector detecting the flux density and/or direction of the magnetic field produced by the magnet can be used to determine the position of the magnet and, thereby, the position of the adjustment mechanism and the reflecting interface. The position indicator may also or alternately comprise a linear bar code or a two dimensional matrix code wherein the position of the reflecting interface is encoded.

In an image relaying device as described herein, the optical system can be configured to provide a real image outside a casing of the image relaying device. The optical system may be configured to provide a real image in the vicinity of the window region, for example, a few millimeters or several millimeters outside the window region. This real image can be detected or sensed by an image sensor of an image detecting device comprising no curved refracting or reflecting surface.

In an image relaying device as described herein, the window region is a first window region and the optical system is a first optical system, wherein the image relaying device further comprises a second optically transparent window region in the proximal end region of the image relaying device and a second optical system in the shaft, wherein the second optical system is similar to the first optical system, wherein the second optical system relays an image produced by the objective lens or by another objective lens to the proximal end region in such a way that the relayed image can be captured through the second window region, wherein the second optical system's optical axis at the second window region is orthogonal or substantially orthogonal to the second optical system's optical axis in the shaft and parallel to the first optical system's optical axis at the first window region.

An image relaying device as described herein can comprise two window regions and two similar optical systems, wherein the optical systems' optical axes at their respective window regions are parallel to each other. Both window regions can be arranged parallel and close to each other. In particular, both window regions can be part of the same optically transparent window element. As an alternative, the window regions can be formed by two different optically transparent window elements. These two different optically transparent window elements can be arranged parallel and/or close to each other or spaced apart from each other. In particular, both window elements can be arranged at opposite sides of the casing of the image relaying device. In the shaft, both optical systems are arranged parallel to each other and both optical systems' optical axes are parallel to each other. In general, both optical systems provide—within the limits of manufacturing tolerance—identical characteristics.

The image relaying device can also comprise more than two optical systems (for example three, four, or five optical systems) and a corresponding number of window regions, wherein all optical systems may provide—within the limits of manufacturing tolerance—identical characteristics.

In an image relaying device as described herein, the directions of propagation of light in the optical systems at their respective window regions can be opposite to each other. In general, the directions of propagation of light originating from the same observed object in the optical systems at their respective window regions are opposite to each other.

In an image relaying device as described herein, the two window regions can be formed by two different window elements which are parallel to each other and arranged at opposite sides of a casing of the image relaying device.

In particular, an image relaying device as described herein is may be an endoscope or an exoscope or a surgical microscope or a borescope or is part of an endoscope or an exoscope or a surgical microscope or a borescope.

An image detecting device for an image relaying device comprises an image sensor, a window element, wherein light passing the window element is detected by the image sensor, and a coupling mechanism for a separable mechanical coupling of the image detecting device to an image relaying device, wherein the image detecting device is configured to be coupled to an image relaying device in such a way that a longitudinal axis of a shaft of the image relaying device is parallel to the window element.

The image detecting device can be configured to be coupled to and functionally combined with an image relaying device as described herein. An image sensor is provided for detecting an image projected onto the image sensor (more particularly onto or into its light sensitive layer) and for generating an (analogue or digital, in particular electronic) image signal representing the detected image. As an example, the image sensor can be a CCD- or a CMOS-sensor with a matrix of pixels, or light sensitive elements. The image sensor can comprise a Bayer-filter, i.e. a matrix of red, green and blue filter elements in front of light sensitive elements. As an alternative, the image detecting device can comprise a number of image sensors and a number of dichroic filters, wherein the dichroic filters allow light within a respective predetermined range of wavelengths only to be detected by each image sensor.

The window of the image detecting device may be arranged parallel to the image sensor. The window can face the image sensor or be integral with the image sensor.

The coupling mechanism can comprise a recess in the casing of the image detecting device, wherein the shape of the recess corresponds to the shape of the proximal end of an image relaying device the image detecting device is provided for. The coupling mechanism can comprise a latching mechanism or a bayonet mechanism or a magnet mechanism allowing to repeatedly couple the image detecting device to an image relaying device and decouple the image detecting device from the image relaying device without damaging either of the devices.

An image detecting device as described herein can further comprise a receiver for receiving, from a position indicator of an image relaying device, information representing the position of a reflecting interface of the image relaying device. The receiver can be configured to receive the information when the image detecting device is coupled to the image relaying device or during the coupling procedure. The receiver can comprise a Hhall sensor or another sensor sensing the direction or flux density of a magnetic field or a bar code reader or a matrix code reader. A Hall sensor or another sensor sensing the direction or the flux density of a magnetic field allows for a determination of the position of a magnet inside the image relaying device. When the position of the reflecting interface inside the image relaying device is unambiguously coupled to the position or orientation of a magnet inside the image relaying device, the position of the reflecting interface can be deduced from the orientation or flux density of a magnetic field produced by the magnet. As an alternative, the position of the reflecting interface can be encoded in a bar code or a matrix code at the outer surface of the casing of the image relaying device, and the bar code reader or matrix code reader can read the encoded position.

An image detecting device as described herein can further comprise a frame positioning circuit determining, from the position information, the position of a region of the image sensor, wherein exclusively image data from within the region are read from the image sensor or exclusively image data from within the region are read from a memory or exclusively image data from within the region are transmitted to a display or exclusively image data from within the region are stored in a memory. The frame positioning circuit may be partially or entirely identical to an image evaluating circuit or to an image data processing circuit. When the reflecting interfaces of different image relaying devices are located at different positions, the images relayed by the image relaying devices are projected onto different regions of the image sensor of the image detecting device. This can be compensated by the frame positioning circuit electing the respective region of the image sensor in response to the position information.

An image detecting device as described herein can be configured to detect a real image provided by the image relaying device.

The image detecting device can be configured to be coupled to an image relaying device providing a real image outside the image relaying device. In this case, the image detecting device can comprise no curved refracting or reflecting interface. Rather, the image sensor can be positioned just behind the window element of the image detecting device. In particular, the image sensor can be integral with the window element of the image detecting device.

An image detecting device as described herein can comprise two image sensors, wherein the image detecting device is configured to receive, in a region between the image sensors, a proximal end region of an image relaying device comprising two optical systems simultaneously relaying two images, in a way that each of the images relayed by one of the two optical systems is received by one of the two image sensors. When the image detecting device comprises two image sensors and is configured to receive a proximal end region of an image relaying device in a region between the image sensors, the image detecting device comprises, in particular, two window elements.

The image detecting device can comprise more than two image sensors, for example three, four, or five image sensors. The image detecting device can be configured to be combined with an image relaying device comprising a corresponding number or a different number of optical systems.

An image detecting device as described herein can further comprise an image evaluating circuit comparing image signals provided by the two image sensors and calculating, from the comparison of the image signals, position information representing the relative positions of reflecting interfaces of the image relaying devices. When the reflecting interfaces in the optical systems of the image relaying device are positioned differently, a misalignment, or offset, of the images received by the image sensors results. From a comparison of the image signals, this offset can be calculated and can be used as a position information as described above. In particular, the position of regions of the image sensors (at least the position of a region of one image sensor) can be calculated, wherein exclusively image data from within this region of these regions are read, stored or transmitted.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a schematic representation of an endoscope10and an image detecting device70. More particularly,FIG. 1shows a longitudinal section through the endoscope10and the image detecting device70. Cross sections of non-transparent objects are shown as hatched areas, cross sections of optically transparent elements (window elements, lenses, prisms) are not hatched.

The endoscope10is one example of an image relaying device according to the present invention. The endoscope10comprises a shaft20. The distal end21of the shaft20forms the distal end11of the endoscope10. The shape of the shaft20is essentially cylindrical with a circular, an elliptical or another cross sectional area. The axis of rotational symmetry of the outer surface of the shaft20or, in case of rotational non-symmetry, the line formed by the centers of the cross sectional areas, is called the longitudinal axis28of the shaft20.

A proximal end region16of the endoscope can provide essentially the same cross section as the shaft20or a different cross section. In the configuration shown inFIG. 1, the proximal end region16of the endoscope10is positioned within a recess76of corresponding shape in the image detecting device70.

The casing13of the example endoscope10shown inFIG. 1comprises at least four openings all of which are hermetically closed. An opening at the distal end21of the shaft20is hermetically closed by an optically transparent window element22. Two openings at opposite sides of the proximal end region16of the endoscope10are hermetically closed by optically transparent window elements39. The optically transparent window elements39are arranged symmetrically with respect to the longitudinal axis28of the shaft20. An opening at the proximal end face of the proximal end region16of the endoscope10is closed by a lid18.

Within the casing13of the endoscope10, two objective lenses30immediately proximal to the window element22at the distal end21of the shaft20, a number of rod lenses33,35,36and two prisms40are arranged. Two tubes31are arranged in parallel inside the shaft20. One of two end guides32is fixed to the proximal end of each tube31. Each tube31holds a number of rod lenses33,35,36. One of the objective lenses30, the rod lenses33,35,36arranged in one of the tubes31and one of the two prisms40form a light path. Both light paths are essentially similar, and are arranged symmetrical with respect to a plane of symmetry, wherein the plane of symmetry is orthogonal to the sectional plane shown inFIG. 1and comprises the longitudinal axis28of the shaft20. Therefore, reference numerals refer to only one of the two light paths.

In each light path, the respective objective lens30produces a real image of an object observed by means of the endoscope10. This real image produced by the objective lens30is relayed to the proximal end region16of the endoscope10by means of the rod lenses33,35,36, wherein each rod lens or each rod lens unit comprising a pair of rod lenses produces, from a real intermediate image distal to the rod lens or rod lens unit, another real intermediate image proximal to the rod lens or rod lens unit. The (identical) optical axes of the objective lens30and the rod lens units33,35,36define the optical axis38of the light path. The prism40comprises a reflecting interface42at an angle of 45 degree with respect to the optical axis38of the light path upstream from (distal to) the reflecting interface42and at an angle of 45 degrees with respect to the optical axis38of the light path downstream from the reflecting interface42. The reflecting interface42reflects the light transmitted by the objective30and the rod lens units33,35,36and, thereby, bends the optical axis38by 90 degrees. Upstream from the reflecting interface42, the optical axis38of the light path is parallel to the longitudinal axis28of the shaft20. Downstream from the reflecting interface42, the optical axis38of the light path is orthogonal to the longitudinal axis28of the shaft20. Downstream from the reflecting interface42the light path leaves the endoscope10through the respective window element39and the optical axis38of the light path crosses the respective window element39.

Each of the prisms40is held, carried, or supported by a respective sliding carriage44. Each sliding carriage44is slidably fixed to a rail14integral with or rigidly connected to the casing13of the endoscope10. The rails14define a predetermined path parallel to the longitudinal axis28of the shaft20and inhibit any motion of the respective carriage44in any direction perpendicular to the rail14.

At each sliding carriage44, an adjusting screw45and a spring46(not shown in sectional view) are provided. One end of the adjusting screw45and one end of the spring46rest on a support15integral with or rigidly connected to the casing13. The other end of the spring46rests at a surface of the sliding carriage44opposite to the support15. The thread of the adjusting screw45engages in a corresponding thread in the sliding carriage44. Therefore, any rotation of the adjusting screw45causes a translational displacement of the sliding carriage44.

In the embodiment shown inFIG. 1, at each sliding carriage44, a magnet55is provided producing a magnet field that can be sensed or detected outside the casing13of the endoscope10.

A notch19is provided in the outer surface of the casing13of the endoscope10. A bore77is provided in a region of the outer surface of the casing73of the image detecting device70which region faces the recess73. In the bore77, a helical spring78and a ball79are provided. In the configuration shown inFIG. 1, the helical spring78presses the ball79into the notch19in the outer surface of the casing13of the endoscope10. The notch19, the helical spring78, and the ball79form a latching mechanism releasably fixing the proximal end region16of the endoscope10inside the recess76in the image detecting device70.

Small clearance between the outer surface of the proximal end region16of the endoscope10and the inner surface of the recess76of the image detecting device70and the latching mechanism19,78,79guarantee a predetermined geometry of the entire system. In the example shown inFIG. 1, two latching mechanisms19,78,79are provided symmetrically. As an alternative, merely one latching mechanism19,78,79, or one or more different latching mechanisms may be provided.

The casing73of the image detecting device70shown inFIG. 1comprises, at opposites sides of the recess76, two optically transparent window elements74hermetically or fluid tightly closing openings in the casing73. Each window element74of the image detecting device70is positioned parallel and opposite to a respective window39of the endoscope10. Behind each window element74of the image detecting device70, i.e. inside the casing73of the image detecting device70, a printed circuit board81with an image sensor82, a Hall sensor85and a data processing unit88are provided in various embodiments. Each image sensor82is parallel to the respective window74and, in the configuration shown inFIG. 1, orthogonal to the optical axis38of one of the light paths of the endoscope10. Each data processing circuit88may be coupled to the respective image sensor82and to the respective Hall sensor85.

Characteristics of optical elements like the objective lenses30and the rod lens units33,35,36rarely precisely conform to their theoretical or design values. Rather, the characteristics are distributed within a region of engineering or manufacturing tolerances. As a consequence, the positions of the real intermediate images and of the most proximal real image to be captured by the image sensor82are distributed. Without any compensation, for example, by means of the sliding carriages44of the present invention, the most proximal real images produced by the most proximal rod lenses36, as shown in the example ofFIG. 1: would rarely be precisely within the planes of the image sensors82but almost always slightly upstream or slightly downstream from the planes of the image sensors82. Thus, the image sensors would be located out of the focal plane for one or both of the light paths, and would capture blurred images in most cases.

In the endoscope10shown inFIG. 1, the distribution of the characteristics of the optical elements30,33,35,36can be compensated for by adjusting the positions of the reflecting interfaces42by means of a rotation of the adjusting screws45and by the resulting displacements of the sliding carriages44. When the positions of the reflective interfaces42are adjusted at the end of a manufacturing process of the endoscope10, the proximal opening of the casing13can be closed by the lid18. The lid18can be welded to the casing13for a hermetical closure.

As a result of the adjustment of the positions of the reflecting interfaces42, the most proximate real images produced by the endoscope10are produced precisely in the planes of the image sensors82. However, as can be seen from the positions of the optical axes38of the optical paths downstream from the reflecting interfaces42, the adjustment of the positions of the reflecting interfaces42results in a lateral displacement of the images projected onto the image sensors82.

This lateral displacement of the images projected by the endoscope10onto the image sensors82is compensated by the data processing circuits88. Each data processing circuit88reads the sensor signal of the respective Hall sensor85. From the sensor signals of the Hall sensors85, the data processing circuits88can calculate the positions of the magnets55at the sliding carriages44. From the calculated positions of the sliding carriages44the data processing circuits88can calculate the positions of the regions83of the image sensors82onto which the endoscope projects the images. Each data processing circuit88instructs the respective image sensor82to provide image data referring to the respective region only. As an alternative, all the image data of the image sensors82are read by the data processing circuits88but the data processing circuits88discard image data not referring to the selected regions83and merely provide image data referring to the selected regions83to a display.

FIG. 2shows a further schematic representation of the endoscope10and the image detecting device70described above with reference toFIG. 1. The sectional plane shown inFIG. 2corresponds to the sectional plane ofFIG. 1.

The configuration shown inFIG. 2is different from the configuration shown inFIG. 1. In the configuration shown inFIG. 2, the proximal end region16of the endoscope10is only partially inserted into the recess76of the image detecting device70. The configuration shown inFIG. 1is an intermediate state temporarily existing when the image relaying device and the image detecting device are combined (to form the system and configuration shown inFIG. 1) or separated.

FIG. 3shows a schematic representation of a further endoscope10and a further image detecting device70. The sectional plane ofFIG. 3corresponds to the sectional planes ofFIGS. 1 and 2. With respect to many features, characteristics and functions, the endoscope10and the image detecting device70shown inFIG. 3are similar to the endoscope and the image detecting device described above with reference toFIGS. 1 and 2. Below, in particular features, characteristics and functions of the endoscope10and the image detecting device70shown inFIG. 3which are different from those of the endoscope and the image detecting device described above with reference toFIGS. 1 and 2are described.

In contrast to the endoscope described above with reference toFIGS. 1 and 2, the endoscope10shown inFIG. 3comprises a mirror41instead of a prism. The mirror41comprises a reflecting layer, for instance an aluminum or silver layer. The surface of this reflecting layer is a reflecting interface.

In contrast to the endoscope described above with reference toFIGS. 1 and 2, no magnets are provided at the sliding carriages44of the endoscope10shown inFIG. 3. Instead, a bar code or—as shown inFIG. 3—two bar codes56are provided at the outer surface of the casing13in the proximal end region16of the endoscope10. These bar codes56numerically encode the positions of the reflecting interfaces42set by means of the adjusting screws45at the end of the manufacturing process.

In contrast to the image detecting device described above with reference toFIGS. 1 and 2, the image detecting device70shown inFIG. 3comprises a bar code reader or—as shown inFIG. 3—two bar code readers86. The bar codes56and the bar code readers86are arranged such that the bar code readers86can read the bar codes56when the proximal end region16of the endoscope10is inserted into the recess86of the image detecting device70. The data processing circuits88receive the position information encoded in the bar codes56and read by the bar code readers86and, depending on the position information, select the regions83of the image sensors82.

FIG. 4shows a schematic representation of a further endoscope10and a further image detecting device70. The sectional plane shown inFIG. 4corresponds to the sectional planes of theFIGS. 1 through 3. With respect to many features, characteristics and functions, the endoscope10and the image detecting device70shown inFIG. 4are similar to the endoscopes and image detecting devices described above with reference toFIGS. 1 through 3. Below, in particular features, characteristics and functions of the endoscope10and the image detecting device70shown inFIG. 4which are different from those of the endoscopes and the image detecting devices described above with reference toFIGS. 1 through 3are described.

Similar to the endoscope described above with reference toFIG. 3, no magnets are provided at the sliding carriages of the endoscope10shown inFIG. 4. Furthermore, no bar code or other indicator provides information regarding the positions of the reflecting interfaces42. Rather, the image detecting device70comprises an image evaluating circuit89comparing image data received from the image sensors82. The image evaluating circuit89calculates, from the image data, the difference of the positions of the reflecting interfaces42. The image evaluating circuit89provides corresponding position information to the data processing circuits88or to the image sensors82and causes them to exclusively provide image data referring to the regions83corresponding to the positions of the reflecting interfaces42. As an alternative, the image evaluating circuit89receives image data from the entire image sensors82but discards image data not referring to the regions83and exclusively forwards image data referring to the regions83to a display.

The functionalities and capabilities and tasks of the data processing circuits88and the image evaluating circuit89can be distributed differently from the schematic representations inFIGS. 1 through 4.

FIG. 5shows a schematic sectional representation of the endoscope10and the image detecting device70described above with reference toFIGS. 1 and 2. The sectional plane ofFIG. 5is orthogonal to the sectional planes ofFIGS. 1 and 2and orthogonal to the longitudinal axis28of the shaft20(cf.FIGS. 1 and 2). Upstream from the reflecting interfaces42, the optical axes38of the light paths are orthogonal to the sectional plane ofFIG. 5, and downstream from the reflecting interfaces42, the optical axes38of the light paths are parallel to the sectional plane ofFIG. 5.FIG. 5shows a configuration different from the configuration shown inFIGS. 1 and 2. Both prisms40are adjusted to the same longitudinal position, and, downstream from the reflecting interfaces, the optical axes38of both light paths are in the sectional plane ofFIG. 5.

In the embodiments described above with reference toFIGS. 3 and 4, sections corresponding to the section shown inFIG. 5are substantially similar to the section shown inFIG. 5.

The rod lens units33,35,36(cf.FIGS. 1, 2) are not in the sectional plane ofFIG. 5. However, the projections of the most proximal rod lenses36are schematically represented by broken lines inFIG. 5.

The sectional plane ofFIG. 5intersects the inclined reflecting interface42. The positions of the optical axes38upstream from the reflecting surface42are indicated by crosses at the centers of the rod lenses36, and the optical axes38downstream from the reflecting surfaces42are represented by broken lines.

FIG. 6shows a schematic sectional representation of a further endoscope10and a further image detecting device70. The sectional plane ofFIG. 6corresponds to the sectional plane ofFIG. 5. The configuration shown inFIG. 6corresponds to the configuration shown inFIG. 5(both prisms40adjusted to the same longitudinal positions).

With respect to many features, characteristics and functions, the endoscope10and the image detecting device70shown inFIG. 6are similar to the endoscopes and the image detecting devices, respectively, described above with reference toFIGS. 1 through 5. Below, in particular features, characteristics and functions of the endoscope10and the image detecting device70shown inFIG. 6which are different from those of the endoscope and the image detecting device described above with reference toFIGS. 1 through 5are described.

In contrast to the endoscopes described above with reference toFIGS. 1 through 5, in the endoscope10shown inFIG. 6, the directions of propagation of light from an object to the image sensors82are parallel not only upstream but also downstream from the reflecting interfaces42. Hence, the window elements39of the endoscope10are not positioned at opposite sides of the casing13of the endoscope10, but side by side, and the image sensors82of the image detecting device70are not positioned at opposite sides of the recess76, but side by side.

One consequence of the configuration shown inFIG. 6is that the images captured by the image sensors82can be compared more easily. Different positions of the reflecting interfaces42(cf.FIGS. 1 through 4) cause an offset of both images in a direction orthogonal to the stereo basis. This offset does not interfere with the disparity caused by the distance of the object.

Another consequence of the configuration shown inFIG. 6is that both image sensors82can be provided on the same printed circuit board81. Additionally, in some embodiments of the general configuration shown inFIG. 6, a single image sensor with an active area of adequate dimensions to capture both images relayed by the reflecting interfaces42on a single active area could be used rather than using two distinct image sensors82. The individual images could then be resolved by a single image processing circuit88or by other means.

FIG. 7shows a schematic sectional representation of a further endoscope10and a further image detecting device70. The sectional plane ofFIG. 7corresponds to the sectional planes ofFIGS. 5 and 6. The configuration shown inFIG. 7corresponds to the configurations shown inFIGS. 5 and 6(all prisms40adjusted to the same longitudinal positions).

With respect to many features, characteristics and functions, the endoscope10and the image detecting device70shown inFIG. 7are similar to the endoscopes and the image detecting devices, respectively, described above with reference toFIGS. 1 through 6. Below, in particular features, characteristics and functions of the endoscope10and the image detecting device70shown inFIG. 7which are different from those of the endoscopes and the image detecting devices described above with reference toFIGS. 1 through 6are described.

In contrast to the endoscopes described above with reference toFIGS. 1 through 6, the endoscope10shown inFIG. 7comprises four parallel light paths formed by four parallel arrangements of rod lenses36. Four similar prisms40are provided at four sliding carriages42, each prism comprising a reflecting interface42bending the optical axis of the corresponding light path by 90 degrees.

The image detecting device70comprises four similar image sensors82. Each of the image sensors82captures the images relayed by a corresponding rod lens36and reflected by a corresponding reflecting interface42.

In the example shown inFIG. 7, a pair of image sensors82are arranged side by side at one printed circuit board81, and another pair of image sensors82are arranged side by side at another printed circuit board81, wherein both circuit boards are arranged at opposite sides of the recess76. Correspondingly, the directions of propagation of light from an object to the image sensors82at the same printed circuit board are parallel, and the directions of propagation of light from an object to image sensors82at different printed circuit boards are anti-parallel. As in the variation to the embodiment ofFIG. 6, a single image sensor with an active area of adequate dimensions to capture a pair of images traveling a parallel path may replace the two distinct image sensors82. As an alternative, the image sensors82can be arranged at different positions, for example one image sensor82at each of four sides of the recess76.

In the example shown inFIG. 7, the endoscope10comprises two window elements39, and each window element39at the endoscope is provided for two parallel light paths. As an alternative, four separate windows can be provided, wherein each window element is allocated to one of the light paths of the endoscope10(similar to the embodiment described above with reference toFIG. 6).

In the example shown inFIG. 7, the image detecting device70comprises two window elements74, and each window element74at the endoscope is provided for one pair of image sensors82. As an alternative, four separate windows can be provided, wherein each window element is allocated to one of the image sensors82.

In the example shown inFIG. 6, the endoscope10can, as an alternative, comprise a single window element39for both light paths (similar to the endoscope shown inFIG. 7) and/or the image detecting device70can comprise a single window element74for both image sensors82(similar to the image detecting device shown inFIG. 7).

FIG. 8shows a schematic sectional representation of a further endoscope10and a further image detecting device70. The sectional plane ofFIG. 8corresponds to the sectional planes ofFIGS. 5 through 7. The configuration shown inFIG. 8corresponds to the configurations shown inFIGS. 5 through 7(all prisms40adjusted to the same longitudinal positions).

With respect to many features, characteristics and functions, the endoscope10and the image detecting device70shown inFIG. 8are similar to the endoscope and the image detecting device, respectively, described above with reference toFIGS. 1 through 7. Below, in particular features, characteristics and functions of the endoscope10and the image detecting device70shown inFIG. 8which are different from those of the endoscope and the image detecting device described above with reference toFIGS. 1 through 7are described.

The endoscope10shown inFIG. 8comprises three parallel light paths, each light path formed by a set of rod lenses36and a prism40comprising a reflecting interface42. Correspondingly, the image detecting device shown inFIG. 8comprises three image sensors82and three windows74allocated to the image sensors82.

In the example shown inFIG. 8, the light paths' optical axes38downstream from the reflecting interfaces42are arranged tangentially, i.e. straight lines comprising the optical axes38downstream the reflecting interfaces42do not intersect in one but in three different points. As an alternative, the optical axes38downstream from the reflecting interfaces42can be arranged radially, i.e. straight lines comprising the optical axes38downstream the reflecting interfaces42intersect in a single point.

In particular in the latter case, the proximal end16of the endoscope10and the recess76of the image detecting device70can be designed such that the endoscope10can be easily rotated with respect to the image detecting device70. For example, both the cross section of the proximal end16of the endoscope10and the cross section of the recess76of the image detecting device can be circular.

The same applies to the endoscope10and the image detecting device described above with reference toFIG. 7, in particular, when the optical axes38downstream from the reflecting interfaces42are arranged radially.

The number of image sensors82of each of the image detecting devices70shown inFIGS. 7 and 8can be less than the number of light paths. In particular, the number of image sensors82may be two. The endoscope10can be rotated with respect to the image detecting device to different predetermined rotational positions in which the image sensors82are optically coupled to different pairs of light paths. When the endoscope's viewing direction is not parallel to the longitudinal axis of the shaft, rotation of the endoscope can rotate the viewing direction on a cone, and stereoscopic imaging in a number of different predetermined directions is facilitated.

In the examples shown inFIGS. 5 through 8, the rails14defining the paths of the sliding carriages44are dovetail guides. As an alternative, other linear guides or linear bearings can be provided.

In each of the examples shown inFIGS. 5 through 8, the image detecting device laterally encloses the proximal end16of the endoscope10completely. As an alternative, the cross section of the image detecting device can be U-shaped or C-shaped, thereby positively holding or locking the proximal end16of the endoscope10into a well defined position without completely enclosing it.

In all the endoscopes described above with reference toFIGS. 1 through 8, the reflecting interfaces42can be part of prisms, mirrors or other optical elements. The reflecting interfaces42and/or other surfaces of prisms40can be curved. The image sensors82can be integral with the optically transparent window elements74.