Abstract:
A visual field apparatus for an image transmission apparatus including a channel that connects the proximal end and the distal end of the visual field apparatus, for inputting the image transmission apparatus, and an optical device on the distal end of the channel that is configured to influence the visual field or the focusing of the image transmission apparatus. A method for preparing an endoscope for a succeeding use including determining a visual field required for the succeeding use, selecting a visual field apparatus with the determined visual field and a channel, and combining the image transmission apparatus with the selected visual field apparatus. A method for autoclaving a visual field apparatus for an image transmission apparatus, including closing the channel on the proximal end so that it is fluid-tight, autoclaving the visual field apparatus after the fluid-tight closing, and opening the channel on the proximal end after autoclaving.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority of German patent application No. 10 2010 022 430.8 filed on Jun. 1, 2010. 
     FIELD OF THE INVENTION 
     The present invention relates to a visual field apparatus for an image transmission apparatus, in particular for an endoscope, to an image transmission apparatus, an endoscope and a method for preparing an endoscope and for autoclaving a visual field apparatus. 
     BACKGROUND OF THE INVENTION 
     The visual field of an endoscope is the spatial area that is recorded by the stationary endoscope or can be recorded by the stationary endoscope. The visual field can be characterized by the spatial angle occupied by the recorded area with reference to the distal end of the endoscope, by the viewing direction and by the angular distance of opposite boundaries of the visual field. The viewing direction is the direction with respect to the distal end of the endoscope in which objects are located that are in the center of the recorded image during observation by the endoscope or are imaged on the center of a light-sensitive sensor or image sensor. 
     Different uses or applications of an endoscope, in particular different medical uses, require various visual fields as a rule, in particular different viewing directions and different sizes of the visual fields. A great number of varying endoscopes therefore exists, with different viewing directions and different sizes of the visual fields. Accordingly, different types of endoscope are kept available in hospitals, medical practices, and other medical installations. Acquisition, maintenance, and readiness of numerous diverse endoscopes—with several units of each type, as a rule—generate considerable costs as a result. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to reduce the expense for acquisition and maintenance of endoscopes with numerous different visual fields. 
     This object is achieved through the contents of the independent claims. 
     Refinements are indicated in the dependent claims. 
     Some embodiments of the present invention are based on the idea of providing a visual field apparatus for an image transmission apparatus, in particular for an endoscope, that includes a channel that links the proximal and distal ends of the visual field apparatus and serves as an intake for the image transmission apparatus, and an optical device on the distal end of the channel that is configured at least to influence either the visual field or the focusing of the image transmission apparatus. 
     The reference to influencing the visual field of the image transmission apparatus does not signify merely cutting off part of the visual field without changing the position and size of the image of an object. Influencing the visual field, instead, means simultaneously modifying the size and/or displacing the position of the image of a particular object. For example, a pane of glass or a window or a glass covering with parallel level or else parallel curved border surfaces influences the visual field only insignificantly or not at all. 
     With one and the same image transmission apparatus, alternatively, it is possible now to combine various visual field apparatuses in order to form endoscopes with different visual fields. A greater number of different visual field apparatuses can be procured and kept in readiness at reasonable cost because of their comparatively simple structure. Every image transmission apparatus can be combined with several different visual field apparatuses. 
     In the event of damage or soiling of the visual field apparatus, it can easily be replaced and the image transmission apparatus can continue to be used. In particular, the visual field apparatus can be replaced and, for example, autoclaved after each medical use. The image transmission apparatus can also be easily replaceable, allowing it to be exchanged, for example in case of a defect, by a new image transmission apparatus, or to be replaced with an image transmission apparatus with different spectral properties. 
     The number of image transmission apparatuses that are to be kept in readiness is thereby drastically reduced. Even when the costs for producing or procuring the individual image transmission apparatuses are in the same order of magnitude as those for a conventional endoscope, the total costs can be drastically reduced if the production costs of the visual field apparatuses are markedly lower than those for a complete endoscope, because the number of required image transmission apparatuses is clearly smaller than the number of conventionally required endoscopes. 
     The optical device on the distal end of the channel, alternatively or in addition to the visual field, can influence the focusing of the image transmission apparatus. Objects that are sharply imaged by the image transmission apparatus onto a given image surface are in one surface. This surface, depending on the optical device, can be flat or domed, symmetrical or asymmetrical to the optical axis of the optical device. Influencing the focusing means, in particular, influencing or modifying the location and/or shape of this surface. 
     The optical device of the visual field apparatus is configured, in particular, at least either to refract or to reflect or to bend light. In particular, the optical device includes at least either a prism or a mirror or lens. With these relatively simple components, the visual field apparatus can be producible at reasonable cost. 
     The optical device of the visual field apparatus is configured, in particular, to change the direction of the illuminating and/or imaging beam path or to modify the divergence of light in the illuminating and/or imaging beam path. 
     The channel of the visual field apparatus can be configured to allow rotation of an image transmission apparatus around its longitudinal axis in the channel. In particular, the cross-sections of the image transmission apparatus and of the channel are adapted to one another for this purpose. For example, by means of circular cross-sections with corresponding radii, it is possible to guide the image transmission apparatus in the channel with little free play and simultaneously low friction, as well as to rotate and axially slide the image transmission apparatus in the channel. Consequently, in rotating the visual field apparatus around the longitudinal axis and correspondingly varying the viewing direction on a conical mantle while simultaneously securing the image transmission apparatus, it is possible to prevent tipping of the image. The endoscope composed of the visual field apparatus and image transmission apparatus thus can always provide an upright image regardless of the viewing direction. 
     Rotatability of the image transmission apparatus in the channel of the visual field apparatus means, in particular, that it can rotate by more than just a small angle, for example by at least 90 degrees, at least 180 degrees, at least 270 degrees, at least 360 degrees or any desired angle. 
     If the visual field apparatus includes a lens or other optically effective component, the focusing can be modified or the sharply imaged plane can be displaced by axially sliding the image transmission apparatus in the channel of the visual field apparatus. This simple type of focusing allows the use of a lens apparatus with a large aperture that generates a correspondingly bright and low-noise image. In comparison with a small aperture, as is often used conventionally, with correspondingly high depth of field and without focusing, the described focusing allows brighter and lower-noise images and/or of the use of lower illumination intensities. 
     If, in addition, a light-sensitive sensor of the image transmission apparatus—possibly together with a rod lens system—can be slid with respect to a lens, object lens or an optically effective component on the distal end of the image transmission apparatus, then at least either the focus or the focal length or size of the visual field can be modified. For a modification of the focal length, for example, at least a first lens or a first part of an object lens is coupled with the visual field apparatus and at least a second lens or a second part of an object lens is coupled with the image transmission apparatus. 
     Alternatively, the visual field apparatus can be employed with an image transmission apparatus that comprises an eyepiece or a coupling to the junction of a video camera on the proximal end instead of an image transmission apparatus. To transmit an image from the distal end to the proximal end of the image transmission apparatus, a rod lens system can be provided, as in the example described above. Alternatively, for example, an arranged bundle of lightwave conductors can be provided to transmit the image to the eyepiece or to the coupling. Foregoing comments on modifying the focus and/or focal length by sliding the visual field apparatus and the image transmission apparatus relative to one another also apply correspondingly for an image transmission apparatus with an eyepiece or a coupling. 
     The visual field apparatus can comprise an adjustment device to adjustably lock the position of an image transmission apparatus in the longitudinal direction in the channel. The adjustment device includes, for example, an adjustment screw, which can be positioned in the form of a sleeve or adjusting nut coaxially in the area of the shaft or in the area of an operating device of the image transmission apparatus. Such an adjustment device can make possible a fine adjustment, which is simultaneously easily performed and precise, of the focus or position of the sharply imaged plane. 
     The visual field apparatus can include one or more lightwave conductors to transmit illuminating light from the proximal end to the distal end of the visual field apparatus to illuminate an object that is to be observed. If the visual field apparatus includes several lightwave conductors to transmit illuminating light, said conductors in particular form an arranged bundle, contrary to an arranged bundle of lightwave conductors suitable for transmitting an image and used in many cases. 
     In addition, the visual field apparatus on the distal end can include a light outlet device to conduct illuminating light into an area outside the visual field apparatus. Said light outlet device can include an illuminating window and/or a prism and/or a lens and/or a mirror. Said light outlet device can be coupled with the distal end by one or more lightwave conductors integrated into the visual field apparatus to transmit illuminating light. Alternatively, the light outlet device can be configured to couple with one or more lightwave conductors integrated into an image transmission apparatus to transmit illuminating light. 
     The light outlet device integrated into the visual field apparatus or combined with one or more lightwave conductors integrated into the visual field apparatus to transmit illuminating light allows a substantial or complete adaptation of the illuminated area to the visual field. 
     The optical device on the distal end of the channel of the visual field apparatus can be insulated against liquids from outside or from the distal direction. For this purpose, a fluid-tight inserted covering glass or a fluid-tight connection can be provided between the optical device itself or the outermost distal element of the optical device on the one hand, and, for example, tubular structures of the visual field apparatus on the other hand. In addition, a fluid-tight insulation of the optical device can be provided from the proximal side or the channel. For this purpose, a fluid-tight inserted additional covering glass or a fluid-tight connection, for example, is provided between the optical device itself or an outermost proximal element of the optical device on the one hand and the inside wall of the channel on the other hand. 
     The fluid-tight insulation of the optical device allows an autoclaving of the visual field apparatus without penetration of moisture into the optical device. The optical properties of the optical device can thus be maintained without restriction even after multiple autoclaving cycles. If the optical device is not insulated against fluids from the proximal direction or the channel, then during autoclaving it is possible to insert a sealing stopper on the proximal end of the channel to avoid penetration of moisture into the channel and into the optical device. Such a sealing stopper can include one or more O-rings or other insulating devices. 
     The visual field apparatus can comprise a shaft, which can be as long as the shaft of the image transmission apparatus or even shorter than it. The visual field apparatus can be configured as a closed, in particular a fluid-tight, sleeve for the image transmission apparatus. In this case the visual field apparatus can make autoclaving of the image transmission apparatus between two uses superfluous. This can also be achieved if the visual field apparatus, if not surrounding the image transmission apparatus in the form of a sleeve completely and fluid-tight, instead is supplemented by a sterile cloth to cover parts of the image transmission apparatus that are not covered or encased by the visual field apparatus. 
     The visual field apparatuses described here can be configured for rigid or flexible image transmission apparatuses, in particular for video endoscopes, endoscopes with rod lens systems or with an arranged bundle of lightwave conductors for transmitting an image from the distal to the proximal area. The visual field apparatus can be configured correspondingly as rigid or flexible for this purpose. The described visual field apparatuses are configured in particular for use with medical endoscopes or are configured to be combined with an image transmission apparatus to form a medical endoscope. For this purpose the described visual field apparatuses are in particular autoclavable or sterilizable by other means or else configured as disposable articles or one-way articles at correspondingly low production costs. 
     The described visual field apparatuses, however, can also be configured for non-medical technical applications or for use with non-medical technical endoscopes or boroscopes. Because of the described visual field apparatuses, it is possible simultaneously to avoid soiling or else damage to an image transmission apparatus, in particular an endoscope, so that said apparatus can continue to be used immediately after exchanging the visual field apparatus without the need for previous expensive cleaning. 
     Each of the described visual field apparatuses can be configured for an image transmission apparatus that is an endoscope with all characteristics, properties and functionalities of an endoscope in the conventional sense of the term. Such an image transmission apparatus, even without one of the described visual field apparatuses, can be used as an endoscope in medical or non-medical technical endoscopic investigations or procedures. For this purpose the image transmission apparatus is, for example, autoclavable, comprises keys or other elements for operation by a user, and delivers a sharp image of objects. 
     Alternatively, each of the described visual field apparatuses can be configured for an image transmission apparatus that, only in combination with the visual field apparatus, comprises all properties and functions required for use in medical or non-medical technical endoscopic investigations or procedures. For example, the image transmission apparatus is not autoclavable or does not deliver a sharp image when it is not combined with a visual field apparatus. 
     Additional embodiments of the present invention are based on the idea of providing an image transmission apparatus with a shaft and at least either a device for optical transmission of an image from a distal end to a proximal end of the shaft or an image sensor for converting an optical image into an image signal, where the shaft is configured to be inserted into a channel in a visual field apparatus that on the distal end of the channel comprises an optical device, which influences the visual field of the endoscope. The image transmission apparatus is configured in particular to generate a sharp image of an object or only to generate such an image when the image transmission apparatus is inserted into a channel of one of the visual field apparatuses described above. The image transmission apparatus can comprise on the distal end of the shaft a fluid-tight inserted transparent closing, in particular a covering glass or an observation window of a transparent material. 
     Additional embodiments of the present invention are based on the idea of providing an endoscope with one of the visual field apparatuses described above and an image transmission apparatus that can be inserted into the channel of the visual field apparatus, in particular the image transmission apparatus described above, where the image transmission apparatus comprises at least either a device for optical transmission of an image from a distal end of the endoscope to a proximal end of the endoscope or an image sensor to convert an optical image into an image signal. 
     Additional embodiments of the present invention are based on the idea, in a method for providing an endoscope, of determining, for a succeeding use of the endoscope, a visual field that is required in the succeeding use, to select a visual field apparatus with the determined visual field, and to combine an image transmission apparatus with the selected visual field apparatus, in particular to insert it into a channel of the selected visual field apparatus in order to form an endoscope. 
     Additional embodiments of the present invention are based on the idea, in a method for autoclaving a visual field apparatus for an image transmission apparatus, with a channel that connects the proximal end and the distal end of the visual field apparatus, for intake of an image transmission apparatus, and an optical device on the distal end of the channel that is configured to influence the visual field of the endoscope, to close off the channel at the proximal end in fluid-tight manner, after fluid-tight closing to autoclave the visual field apparatus and after autoclaving to open up the channel on the proximal end. 
     The methods described above are performed in particular with one of the visual field apparatuses described above and/or with the image transmission apparatus described above. The visual field apparatuses described above and the image transmission apparatuses described above are configured and suited in particular for performing one of the methods cited above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are described in greater detail hereinafter with reference to the appended drawings, which are as follows. 
         FIG. 1  is a schematic depiction of an image transmission apparatus. 
         FIG. 2  is a schematic depiction of a visual field apparatus for an image transmission apparatus. 
         FIG. 3  is a schematic depiction of a combination of an image transmission apparatus with one of several visual field apparatuses. 
         FIG. 4  is a schematic depiction of a combination of an image transmission apparatus with one of several visual field apparatuses. 
         FIG. 5  is a schematic depiction of an image transmission apparatus. 
         FIG. 6  is a schematic depiction of a visual field apparatus for an image transmission apparatus. 
         FIG. 7  is a schematic depiction of an image transmission apparatus. 
         FIG. 8  is a schematic depiction of a visual field apparatus for an image transmission apparatus. 
         FIG. 9  is a schematic depiction of an image transmission apparatus. 
         FIG. 10  is a schematic depiction of a visual field apparatus for an image transmission apparatus. 
         FIG. 11  is a schematic depiction of an image transmission apparatus. 
         FIG. 12  is a schematic depiction of a visual field apparatus for an image transmission apparatus. 
         FIG. 13  is a schematic flow diagram for a method for providing and autoclaving an endoscope. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Each of  FIGS. 1 through 10  shows a schematic depiction of an endoscope or of components of an endoscope or of the assembly of components of an endoscope. At the same time, each of  FIGS. 1 through 10  shows essentially a depiction of a section along a plane that contains a longitudinal axis of the endoscope. The depiction of lightwave conductors or electrical lines can depart from a pure sectional depiction in order to clarify the spatial arrangement of the same. The endoscope or components of the endoscope can be partly or entirely rotationally symmetrical to the longitudinal axis of the endoscope. 
     In each of  FIGS. 1 through 10 , an image transmission apparatus or at least parts of an image transmission apparatus are depicted. For purposes of a transparent depiction, however, components and characteristics of the image transmission apparatuses are partly provided with reference numbers only in  FIGS. 1, 5, 7 and 9 . In  FIGS. 2, 6, 8 and 10 , many components and characteristics of the image transmission apparatuses are not provided with reference numbers in order to avoid overloading the illustrations. 
       FIG. 1  shows an image transmission apparatus  11 . The image transmission apparatus  11  can be an endoscope with all characteristics and properties—in particular, performance characteristics and functionalities—of an endoscope in the conventional sense of the term. In particular, the image transmission apparatus can be configured and suited for use in medical or non-medical technical endoscopic investigations or procedures without a visual field apparatus as it is described hereinafter with reference to the other illustrations. For this purpose the image transmission apparatus is, for example, autoclavable, comprises keys or other elements for operation by a user, and supplies a sharp image of objects. 
     Alternatively, the image transmission apparatus  11  can be configured so that, only in combination with a visual field apparatus as it is described hereinafter with reference to the other illustrations, it comprises all the properties and functions required for use in medical or non-medical technical endoscopic investigations or procedures. For example, the image transmission apparatus  11  is not autoclavable or does not supply a sharp image if it is not combined with a visual field apparatus. 
     The image transmission apparatus  11  comprises a distal end  12  and a proximal end  13 . A shaft  20  of the image transmission apparatus  11  comprises an inner tube  21  and an outer tube  22 . On the distal end  12  the shaft  20  comprises an observation window  24  and one or more illuminating windows  25 , which each is made of glass or another transparent material. The observation window  24  and the illuminating window  25  are, in particular, optically separated from one another, for example by a distal edge of the inner tube  21 . Alternatively, a single window is provided that assumes the functions of the observation window  24  and of the illuminating window or windows  25 . 
     On the proximal end  13  the image transmission apparatus  11  comprises a handling device  30  with a distal housing part  31  and a proximal housing part  32 . The distal housing part  31  of the handling device  30  is mechanically connected, in particular joined, with the proximal end of the outer tube  22  of the shaft  20 . The proximal end of the inner tube  21  is also mechanically connected with the distal housing part  31  of the handling device  30 , in this example by a screwing device  34  with a lock nut  35 . 
     The distal housing part  31  and the proximal housing part  32  of the handling device  30  can rotate relative to one another with respect to the longitudinal axis of the image transmission apparatus  11  and in particular of the shaft  20  and/or can be slid axially. Between the distal housing part  31  and the proximal housing part  32  of the handling device  30 , one or more O-rings  37  are provided for fluid-tight insulation of the interior of the handling device  30  and of the shaft  20  on the one hand, and with respect to the outside on the other hand. 
     On the handling device  30 , in particular on the distal housing part  32  of the handling device  30 , it is possible to provide switches, keys or other operating elements with which to control, for example, the illumination, recording of images or their storage. For example, magnetic sensors  39 , shown in  FIG. 1 , are connected with the sensor carrier  43  via electric lines and with the plug-in connection  44  via said carrier. 
     On the distal end of the shaft  20 , a light-sensitive sensor  41  and an object lens  42  are positioned in the inner tube  21 . The object lens  42  images objects close to the distal end  12  of the image transmission apparatus  11  on the light-sensitive sensor  41 . The light-sensitive sensor  41  is positioned on the distal end of a sensor carrier  43 , which extends in rod shape in the inner tube  21  of the shaft  20  and farther all the way to the proximal end of the proximal housing part  32  of the handling device  30 . The sensor carrier  43 , as shown in  FIG. 1 , is pressed by a spring against the proximal end of the proximal housing part  32  of the handling device  30 , where it supports itself. Alternatively, the sensor carrier  43  is fastened on the proximal end of the proximal housing part  32  of the handling device  30 . 
     One or more electrical or optical signal lines in or on the sensor carrier  43  couple the light-sensitive sensor  41  with a plug-in connection  44  on the proximal end of the handling device  30 . An O-ring  46  is provided for fluid-tight insulation between the sensor carrier  43  and the proximal housing part  32  of the handling device  30 . An additional O-ring  47  is provided for fluid-tight insulation between the sensor carrier  43  and a visual field apparatus that is described subsequently with reference to  FIG. 2 . 
     Lightwave conductors  48  are positioned between the inner tube  21  and the outer tube  22  of the shaft  20  of the image transmission apparatus  11 . The lightwave conductors  48  extend from the illuminating window or windows  25  all the way to a passageway or a plug-in connection  49  on the proximal end of the proximal housing part  32  of the handling device  30 . Instead of the illuminating window  25  inserted as a transparent component, the distal ends of the lightwave conductors  48  can simply be cemented on the distal end of the shaft  20  of the image transmission apparatus  11  by means of an (optionally transparent) cement. By grinding and polishing the distal front surface of the shaft  20  with the ends of the lightwave conductors  48  and the cement, an optically high-caliber light outlet surface can be produced. 
     A signal cable  53  with a plug-in connection  54  can be connected with the plug-in connection  44  on the proximal end of the sensor carrier  43 . It is possible, for example, for the signal cable  42  to replace electrical signals and electrical power between the light-sensitive sensor  41  and a device not shown in  FIG. 1  for preparing and depicting images. 
     A lightwave conductor cable  58  with a plug-in connection  59  can be coupled with the passageway or the plug-in connection  49 . Light from an external light source, not shown in  FIG. 1 , can be conducted to the distal end  12  of the image transmission apparatus  11  by the lightwave conductor cable  58 , the plug-in connections  49 ,  59  and the lightwave conductors  48 , in order to illuminate objects close to the distal end  12  of the image transmission apparatus  11 . 
     The image transmission apparatus  11  described with reference to  FIG. 1  comprises, as mentioned, a light-sensitive sensor  41 , which converts light intensities present on its light-sensitive surface into analog or digital electrical or else optical signals. These signals constitute the image generated by the object lens  42  on the light-sensitive surface of the light-sensitive sensor  41  in analog or digital form. The signals are transmitted by the aforementioned electrical lines or by optical lightwave conductors in the sensor carrier to the proximal end  13  of the image transmission apparatus and further by the signal cable  53  to the apparatuses, not shown in  FIG. 1 , for evaluating signals and depicting the image (for example on a screen). 
     Alternatively, the image transmission apparatus  11  comprises a rod lens system, an arranged bundle of lightwave conductors or other optical device for transmitting the image generated by the object lens to the proximal end  13  of the image transmission apparatus  11 . The image can then be observed on the proximal end  13  of the image transmission apparatus  11 , for example by an eyepiece, can be converted into analog or digital electrical or else optical signals by a light-sensitive sensor, or can be transmitted further by an arranged bundle of lightwave conductors. 
     As mentioned, the image transmission apparatus  11  can be configured and suited to be used as an endoscope independently of the visual field apparatus described below with reference to  FIG. 2 . For this purpose, in particular the light-sensitive sensor  41  and the object lens  42  are configured and suited to capture, without further devices for refracting or reflecting light, a sharp image of an object close to the distal end  12  of the image transmission apparatus  11 . 
     Alternatively, the image transmission apparatus  11  is configured to be used as an endoscope only in combination with the visual field apparatus described below with reference to  FIG. 2 . For this purpose, in particular the light-sensitive sensor  41  and the object lens  42  are configured and suited to capture a sharp image of an object close to the distal end  12  of the image transmission apparatus  11  only in combination with an additional device for refracting or reflecting light on the visual field apparatus described below. In addition, in this case the object lens  42  can be dispensed with. 
       FIG. 2  shows a schematic depiction of a sleeve  60  from a visual field apparatus  61  and a proximal sleeve part  70  for the image transmission apparatus  11  described above with reference to  FIG. 1 . The visual field apparatus  61  is configured here simultaneously as a distal sleeve part, which forms the sleeve  60  together with the proximal sleeve part  70 . Independently of whether the image transmission apparatus  11  can be used as an endoscope even without the visual field apparatus  61 , the image transmission apparatus  11  and visual field apparatus  61  together form an endoscope  10 . 
     The visual field apparatus  61  includes a shaft  62  with an observation window  63  and an illuminating window  64  on the distal end. The observation window  63  and illuminating window  64  are adapted in arrangement, size and shape to the observation window  24  or illumination window  25  on the distal end  12  of the shaft  20  of the image transmission apparatus  11 . The observation window  63  and illuminating window  64  are optically separated from one another, for example by a frame  65  made of metal or other non-transparent material around the observation window  63 . Alternatively, a single window is provided that assumes the functions of the observation window  63  and of the illuminating window or windows  64 . In this case it can be useful or necessary to reduce scattered light, for example by blackening the window on a boundary between the two areas that assume the functions of the illuminating window  64  and observation window  63 . O-rings  66 ,  67  and a thread  68  are provided on the visual field apparatus  61 ; their function is described hereinafter. 
     On the proximal sleeve part  70 , a sleeve  71  is provided that is rotatably connected with the proximal sleeve part  70  by an axial fastening  72 . The axial fastening  72  includes, for example, an open or closed ring, which engages in ring-shaped grooves on the proximal sleeve part  70  and on the sleeve  71 . The axial fastening  72  allows rotation of the sleeve  71  relative to the proximal sleeve part  70 , but prevents a relative axial sliding. In addition the sleeve  71  includes an O-ring  73  for fluid-tight insulation between the proximal sleeve part  70  and the sleeve  71 . 
     The proximal sleeve part  70  includes on the proximal end an aperture  74  for intake of the proximal end of the sensor carrier  43  and of the plug-in connection  44 . In addition, the proximal end of the proximal sleeve part  70  can be configured to provide a fluid-tight connection with a mantle  75  of the data cable  53  or with a mantle  75  for the data cable  53 . In addition, the proximal sleeve part  70  comprises an aperture  76  or a window through which the lightwave conductor cable  58  can be optically coupled with the lightwave conductors  48 . 
     Configured on the sleeve  71  is a counter-thread  78  to the thread  68  on the visual field apparatus  61 . The thread  68  on the visual field apparatus  61  and the counter-thread  78  on the sleeve  71  can be screwed to one another to provide a separable mechanical connection between the visual field apparatus  61  and the proximal sleeve part  70  via the sleeve  71  and the axial fastening  72 . In addition, by means of the reciprocal engagement of the thread  68  on the visual field apparatus  61  and of the counter-thread  78  on the sleeve  71 , a relative rotation of the sleeve  71  with respect to the visual field apparatus  61  is converted into an axial sliding of the same and thus a relative axial sliding of the visual field apparatus  61  and of the proximal sleeve part  70 . 
     In addition, the proximal sleeve part  70  comprises keys  79 , which are positioned opposite the magnetic sensors  39  and contain magnets. The keys  79  are configured in such a way that pressure or force on a key  79  causes a movement of a magnet positioned inside it, said movement being recorded by the magnetic sensor  39  opposite. The keys comprise, for example, an elastic material and are insulated to be fluid-tight and, in particular, sterile. Alternatively to the keys  79  and magnetic sensors  39 , other devices can be provided as user interfaces. 
     Proximally from the observation window  63 , a prism  87  is positioned in the observation beam path on the visual field apparatus  61 . Proximally from the illuminating window or windows  64 , one or more prisms  88  are positioned in the illuminating beam path. The prisms  87 ,  88  can each be configured as a single piece along with the observation window  63  or the illuminating window  64 . The prisms  87 ,  88  divert light by refraction and/or reflection to surfaces (especially by total reflection), thus modifying its direction. Thus the prisms  87 ,  88  influence the visual field and/or the recorded area of the endoscope  10  made up of the image transmission apparatus  11  and visual field apparatus or sleeve  60 . As described hereinafter in greater detail with reference to  FIGS. 3 and 4 , it is thus possible, with one and the same image transmission apparatus  11  in combinations with different visual field apparatuses  61 , to produce different visual fields that are distinguished from one another by their direction and size. 
     The sleeve  60 , consisting of the visual field apparatus  61  and proximal sleeve part  70  with the sleeve  71 , is configured in such a way that its inner surface is contiguous with the outer surface of the image transmission apparatus  11  or else is only at a small distance from it. In addition, the visual field apparatus  61 , the proximal sleeve part  70  and the endoscope  11  are configured in such a way that a relative axial sliding of the visual field apparatus  61  and of the proximal sleeve part  70  causes a corresponding relative axial sliding of the distal housing part  31  and of the proximal housing part  32  of the operating device  30  of the image transmission apparatus  11 . A relative axial sliding of the visual field apparatus  61  and of the sleeve part  70 —for example, caused by a relative rotation of the sleeve  71  with respect to the visual field apparatus  61 —can thus, for example, cause a displacement of the focus or arrangement of the light-sensitive sensor  41  relative to the object lens  42 . 
     In addition, the visual field apparatus  61  and the proximal sleeve part  70  can be configured in such a way that a rotation of the visual field apparatus  61  is transmitted to the distal housing part  31  of the handling device  30  and to the shaft  20  and/or that a rotation of the proximal sleeve part  70  is transmitted to the proximal housing part  32  of the handling device  30 . For this purpose, the visual field apparatus  61 , proximal sleeve part  70  and housing parts  31 ,  32  of the handling device  30  comprise, for example, grooves and studs or other rigid or elastic catch-locking, mutually engaging details, which are not shown in the illustrations. Thus, for example, it is possible to modify a viewing direction of the endoscope  10  by rotating the proximal sleeve part  70  on the one hand with respect to the visual field apparatus  61  and sleeve  71  on the other hand. 
     The O-rings  66 ,  67 ,  73  on the visual field apparatus  61 , on the proximal sleeve part  70  and on the sleeve  71  and the O-ring  47  on the image transmission apparatus  11  provide a fluid-tight insulation of the sleeve  60 . In particular, the O-rings  66 ,  67 ,  73 ,  47  prevent penetration of non-sterile, liquid, gaseous or solid material into the sleeve  60  or the release of non-sterile material from the sleeve  60 . After each use of the endoscope  10  with the image transmission apparatus  11  and the sleeve  60  in a medical procedure, it is therefore necessary only to sterilize, in particular to autoclave, the sleeve  60 . The image transmission apparatus  11  itself must not be exposed to the thermal and mechanical impact of autoclaving. This functionality of the sleeve  60  made up of the visual field apparatus  61  and proximal sleeve part  70  is an optional functionality. 
     The frame  65 , which surrounds the observation window  63  for optical insulation, with the sleeve as described above with reference to  FIG. 2 , widens here in tubular form. The proximal edge of the frame  65 , when the image transmission apparatus  11  is inserted into the sleeve  60 , is configured to be contiguous and optically close to the distal edge of the inner tube  21  of the shaft  20  of the image transmission apparatus  11  and to prevent or reduce the coupling of illuminating light into the observation beam path. 
     In the image transmission apparatus presented above with reference to  FIG. 1  and the sleeve presented above with reference to  FIG. 2 , the viewing direction and visual field are already pre-established by the image transmission apparatus. In the image transmission apparatus  11  shown in  FIG. 3  and the sleeve  60  shown in  FIG. 4 , a viewing direction that departs from the longitudinal axis of the image transmission apparatus  11  and a visual field that is not symmetrical with this longitudinal axis are generated only by the sleeve  60 , in particular the prisms  87 ,  88 . The materials and geometries of the prisms  87 ,  88  determine the angle between the viewing direction and the longitudinal axis and the position of the visual field or of the area that is illuminated by the lightwave conductors  48  and through the illuminating windows  25 ,  64  and recorded by the light-sensitive sensor  41  by means of the object lens  42 , observation windows  24 ,  63  and the prism  87 . 
     If the visual field apparatus  61  with the observation window  63 , illuminating window or windows  64  and the prisms  87 ,  88  can rotate with respect to the image transmission apparatus  11  around its longitudinal axis, then by rotating the visual field apparatus  61  and simultaneously fixing the image transmission apparatus  11  (for example by the proximal sleeve part  70 ), the viewing direction of the endoscope  10  on a conical mantle can be modified without causing the recorded image to be tipped. 
       FIGS. 3 and 4  show schematic depictions of the alternative combination of an image transmission apparatus  11  with various visual field apparatuses  61  to produce various visual fields.  FIG. 3  shows various visual field apparatuses  61 , which in combination with the image transmission apparatus  11  result in various viewing directions  81 ,  82 ,  83 ,  84  with an angle to the longitudinal axis of the image transmission apparatus  11  and of the visual field apparatus  61  of approximately 90 degrees, approximately 60 degrees, approximately 30 degrees and approximately zero degrees. Angles of 15 degrees, 45 degrees, 75 degrees or other angles, or any angle that can be selected within an angle interval, can be produced using corresponding visual field apparatuses. 
       FIG. 4  shows various visual field apparatuses  61 , which in combination with an image transmission apparatus  11  at essentially the same viewing direction  83  produce visual fields of various size or angles of various size between opposite boundaries  85  of the visual fields. This combinational ability is also true of the image transmission apparatuses and visual field apparatuses described hereinafter with reference to  FIGS. 5 through 10 . 
       FIG. 5  shows a schematic depiction of an image transmission apparatus  11 , similar to the image transmission apparatus described above with reference to  FIG. 1 . Similarly as in the image transmission apparatus described above with reference to  FIG. 1 , in the image transmission apparatus  11  shown in  FIG. 5  the object lens  42  and visual field are symmetrical and the viewing direction is parallel to the longitudinal axis of the image transmission apparatus  11  or of its shaft  20 . The object lens  42  is optional. 
     Contrary to the image transmission apparatuses described above with reference to  FIG. 1 , the image transmission apparatus  11  shown in  FIG. 5  comprises no lightwave conductors or other devices for transmitting illuminating light to the distal end  12  or for other type of illumination of an observed object. The shaft  20  of the image transmission apparatus  11  consequently can have a markedly smaller cross-section. 
       FIG. 6  shows a schematic depiction of a sleeve  60 , consisting of a visual field apparatus  61  and a proximal sleeve part  70 , for the image transmission apparatus  11  described above with reference to  FIG. 5 . The sleeve shown in  FIG. 6  and in particular the visual field apparatus  61  resemble in a few particulars and characteristics the sleeves  60  and/or visual field apparatus  61  describe above with reference to  FIG. 2 . The visual field apparatus  61  shown in  FIG. 6  is distinguished from the visual field apparatus described above with reference to  FIG. 2 , among other ways, by a guide tube  89  in the shaft  62 . The lumen of the guide tube  89  forms a channel  90 , which extends along the shaft  62  of the visual field apparatus  61  from the proximal end to the distal end of the shaft  62 . The cross-section of the channel  90  is adapted to the shaft  20  of the image transmission apparatus  11 , so that the shaft  20  of the image transmission apparatus  11 , with little free play and friction, rotates around its longitudinal axis in the channel  90  and can be slid parallel to the longitudinal axis. 
     A prism  87  is positioned proximally from the observation window  63 , similarly as with the sleeve described above with reference to  FIG. 2 . The material and geometry of the prism  87  cause the visual field, illuminated and recorded by the image transmission apparatus  11 , to be asymmetrical with the longitudinal axis of the image transmission apparatus  11  or the viewing direction to be non-parallel to this longitudinal axis. Similarly as described above with reference to  FIGS. 3 and 4 , it is possible with one and the same image transmission apparatus  11 , in combinations with different visual field apparatuses  61 , to produce different viewing fields, which are distinguished with respect to their direction and size. 
     Outside the guide tube  89  but inside the shaft  62 , lightwave conductors  91  run from an aperture or a junction  76  on the proximal end of the sleeve  60  all the way to a ring-shaped illuminating window  64 , or to several such windows, on the distal end of the visual field apparatus  61 . Instead of the illuminating window or windows  64  inserted as transparent components, the distal ends of the lightwave conductors  91  can simply be cemented in place on the distal end of the shaft  62  of the visual field apparatus  61  by means of an (optionally transparent) cement. By grinding and polishing the distal front surface of the shaft  62  with the ends of the lightwave conductors  48  and the cement, an optically high-caliber light outlet surface can be produced. 
     By means of a lightwave conductor cable that is not shown in  FIG. 5  and is connected with the aperture or the junction  76 , light can be conducted from an external light source by the lightwave conductors  91  to the distal end of the visual field apparatus  61  in order to illuminate there an object outside the sleeve  60 . The arrangement of the illuminating window or windows  64  and of the distal ends of the lightwave conductors  91  causes the illuminated visual field to include the visual field recorded by the image transmission apparatus  11  or essentially to correspond to it. 
       FIG. 7  shows a schematic depiction of an image transmission apparatus  11  similar to the image transmission apparatus described above with reference to  FIG. 5 . Contrary to the image transmission apparatus described above with reference to  FIG. 5 , the image transmission apparatus  11  shown in  FIG. 7  comprises no device for modifying the focus or varying the distance between the light-sensitive sensor  41  and the object lens  42 . The object lens  42  is optional. 
       FIG. 8  shows a schematic depiction of a sleeve  60 , consisting of a visual field apparatus  61  and a proximal sleeve part  70 , for the image transmission apparatus  11  described above with reference to  FIG. 7 . The visual field apparatus  61  shown in  FIG. 8  largely resembles the visual field apparatus described above with reference to  FIG. 6 . The visual field apparatus  61  shown in  FIG. 8  comprises on its distal end a lens  92  in the observation beam path, which is not shown in the sleeves described above with reference to  FIGS. 2 and 6  but which can optionally be provided as well. 
     As already described with reference to  FIG. 2 , it is also possible in the visual field apparatuses illustrated in  FIGS. 6 and 8  to produce a relative axial sliding of the visual field apparatus  61  and of the proximal sleeve part  70  by rotating the sleeve  71  relative to the visual field apparatus  61 . In the combination of the sleeve  60  with the image transmission apparatus  11  as shown in  FIG. 8 , a relative axial sliding of the visual field apparatus  61  and of the proximal sleeve part  70  produced in this way or otherwise causes a relative axial sliding of the image transmission apparatus  11  and of the visual field apparatus  61 . The result, in particular, is a relative axial sliding of the light-sensitive sensor  41  and in some cases of the object lens  42  on the one hand and of the object lens  92  on the distal end of the visual field apparatus  61  on the other hand. This causes a modification in focusing or a sliding of the plane imaged by the object lens  92  on the visual field apparatus  61  and in some cases by the object lens  42  of the image transmission apparatus  11  sharply on the light-sensitive sensor  41 . 
     Similarly as in the image transmission apparatuses described above with reference to  FIGS. 1 and 5  and the visual field apparatuses described above with reference to  FIGS. 2 and 6 , a relative rotatability of the image transmission apparatus  11  and of the visual field apparatus  61  can also be provided in the image transmission apparatus  11  described with reference to  FIG. 7  and the visual field apparatus  61  described with reference to  FIG. 8 . Thereby, as described above, rotation of the viewing direction of the endoscope  10  on a conical mantle can become possible without tipping of the image. 
       FIG. 9  shows a schematic depiction of an image transmission apparatus  11  similar to the image transmission apparatus presented above with reference to  FIG. 7 . The image transmission apparatus shown in  FIG. 9  is distinguished from the image transmission apparatus described with reference to  FIG. 7  by a somewhat different configuration of the handling device  30  with a groove on the proximal front side in which O-rings  94  are positioned. In addition, inside the handling device  30  a circuit board is shown with an analog and/or digital electronic switch, with which the magnetic field sensors  39  and the light-sensitive sensor  41  are coupled, and which, for example, is configured for signal preparation or signal processing. 
       FIG. 10  shows a schematic depiction of a visual field apparatus  61  similar to the visual field apparatus described above with reference to  FIG. 8 . The visual field apparatus  61  shown in  FIG. 10 , however, is configured and foreseen for use without a proximal sleeve part. Instead, the visual field apparatus  61  is configured to engage in the aforementioned proximal-front-side groove of the handling device  30  of the image transmission apparatus  11 . O-rings  94  on the handling device  30  and on the visual field apparatus  61  are configured and positioned for fluid-tight insulation of the connection between the proximal end of the visual field apparatus  61  and the handling device  30  of the image transmission apparatus  11 . 
     The visual field apparatus  61  shown in  FIG. 10  comprises an eccentric arrangement of the guide tube  89  in the shaft  62 . This results, among other things, in a correspondingly asymmetrical arrangement of the observation window  63  and of the illuminating window  64  as well as of the distal ends of the lightwave conductors  91 . Proximally from the observation window  63 , the visual field apparatus  61  comprises a prism  87 , which diverts light impinging through the observation window  63  by total reflection on surfaces of the prism  87  to the object lens  92  and by means of this to the light-sensitive sensor  41  of the image transmission apparatus  11 . 
     Also in the visual field apparatus shown in  FIG. 10 , instead of using illuminating windows  64  inserted as transparent components, the distal ends of the lightwave conductors  91  can simply be cemented in on the distal end of the shaft  62  of the visual field apparatus  61  by means of an (optionally transparent) cement. By grinding and polishing the distal front surface of the shaft  62  with the ends of the lightwave conductors  48  and the cement, an optically high-caliber light outlet surface can be produced. 
     On the proximal end of the object lens  92 , a covering glass  93  is positioned that provides fluid-tight insulation from the channel  90  for the optical device with prism  87  and object lens  92  on the distal end of the visual field apparatus  61 . The optical device with prism  87  and object lens  92  is thus completely encapsulated to be fluid-tight by the observation window  63  in the distal direction and by the covering glass  93  in the proximal direction. The visual field apparatus  61  can therefore be autoclaved without restriction, with no negative impact on the optical properties of the optical device on the distal end. 
     Similarly as the visual field apparatus  61  described above with reference to  FIG. 10 , so too the visual field apparatuses described above with reference to  FIGS. 2, 6 and 8  can be configured contrary to the above illustration for use without a proximal sleeve part  70 . To allow nevertheless for sterile enclosure or sheathing of the image transmission apparatus  11 , a sterile cloth can be used. Said sterile cloth can be proximally connected with the visual field apparatus  61 . 
     Each of the visual field apparatuses described with reference to  FIGS. 2, 4, 6, 8 and 10  can be configured for different visual fields, in particular for different viewing directions and different sizes of the visual fields. As already mentioned, so too the image transmission apparatuses described with reference to  FIGS. 5 through 10 , similarly as described above with reference to  FIGS. 3 and 4 , can be combined with different visual field apparatuses to form endoscopes with varying visual fields. 
     Each of the image transmission apparatuses described above with reference to  FIGS. 1, 3, 5 and 7  can comprise, in the handling device on the proximal end, one or more circuit boards with one or more analog or digital electronic switches for signal preparation or signal processing, as explained above in conjunction with  FIG. 9 . 
     As described above with reference to  FIGS. 1 and 2 , it is also possible with the visual field apparatuses presented above in conjunction with  FIGS. 6, 8 and 10  to provide a common window or a one-piece transparent component in each case instead of the separate observation windows and illuminating windows. In this case, a light passes through said single window to illuminate an object in one direction and also reflected or scattered light goes from the illuminated object in the reverse direction. 
       FIG. 11  shows a variant on the image transmission apparatus  11  described above in conjunction with  FIG. 5 . The image transmission apparatus  11  shown in  FIG. 11  comprises, instead of a sensor carrier  43 , an optical carrier  96 . The optical carrier  96 , similarly as the sensor carrier of the image transmission apparatuses presented above, is pressed in proximal direction by a spring and supports itself on the proximal housing part  32  of the handling device  30 . The optical carrier  96  is of tubular configuration in the shaft  20  of the image transmission apparatus  11  and contains an arrangement of rod lenses  97 . The optical carrier bears a prism device  98  on the proximal end of the arrangement of the rod lenses  97  in the handling device  30 , with several, in particular three, light-sensitive sensors  41 . The three light-sensitive sensors  41  are coupled with an electronic switch on a circuit board  95 . 
     Instead of the arrangement shown in  FIG. 11  with three sensors  41  on a prism device  98 , it is possible to provide a different number of sensors or just one sensor, which is sensitive to light with various wavelengths. CMOS or CCD sensors, for example, can be used as sensors. In addition, instead of one or more sensors, it is possible to provide an eyepiece for direct observation by the human eye or a coupling for connecting a video camera on the proximal end of the image transmission apparatus  11 . 
     The object lens  42  is fastened on the distal end of the shaft  20  of the image transmission apparatus  30  and thus has an unchangeable position relative to the distal housing part  31  of the handling device  30 . The rod lenses  97 , prism arrangement  98  and light-sensitive sensors  41  are fastened on the optical carrier  81 , which supports itself on the proximal housing part  32  of the handling device  30 . The rod lenses  97 , prism arrangement  98  and light-sensitive sensors  41  therefore are at an unchangeable position relative to the proximal housing part  32  of the handling device  30 . A relative sliding of the proximal housing part  32  and of the distal housing part  31  of the handling device  30  thus causes a relative sliding of the object lens  42  on the one hand with respect to the arrangement of rod lenses  97 , of the prism device  98  and light-sensitive sensors  41  on the other hand. 
     Light entering through the observation window  24  into the image transmission apparatus  11  is transmitted from the object lens  42  and the arrangement of rod lenses  97  to the proximal end  13  of the image transmission apparatus  13 , split up by the prism device  98  into several wavelength ranges, and depending on the wavelength is imaged onto one (or more) of the sensors  41 . The light-sensitive sensors convert the light into electric signals, which are prepared and processed, in particular reinforced and digitized, by the electronic switch on the circuit board  95 . 
       FIG. 12  shows a sleeve  60  with a visual field apparatus  61  that forms a distal sleeve part, and with a proximal sleeve part  70  similar to the visual field apparatus described above in conjunction with  FIG. 8 . The visual field apparatus shown in  FIG. 12 , however, is configured in such a way that the distal housing part  31  of the handling device  30  and the shaft  20  are slidable with respect to the visual field apparatus  61 . Thus, both the object lens  42  of the image transmission apparatus  11  on the one hand and the arrangement of rod lenses  97 , prism device  98  and light-sensitive sensors  41  on the other hand are moveable independently of one another relative to the object lens  92  on the distal end of the visual field apparatus  61 . Thus, with corresponding configuration of the object lens  92  on the distal end of the visual field apparatus  61 , of the object lens  42  on the distal end of the image transmission apparatus  11 , of the arrangement of rod lenses  97 , of the prism device  98  and of the light-sensitive sensors  41 , it becomes possible both to displace the focal length and/or to displace the size of the visual field as well as to focus or displace the surface sharply imaged on the light-sensitive sensors  41 . 
     The described displacement of the focal length and focus is possible not only with the image transmission apparatus  11  described above with reference to  FIG. 11  but also, for example, in combining the image transmission apparatus  11  presented above with reference to  FIG. 5  with one of the visual field apparatuses described above in conjunction with  FIGS. 8 and 12 . In addition, it is possible to displace the focal length and focus by combining the image transmission apparatus presented above with reference to  FIG. 1  with the visual field apparatus presented above in conjunction with  FIG. 2  if the latter, contrary to the depiction in  FIG. 2 , comprises an object lens or lens on the distal end. 
     The described displacement of the focal length and focus requires, as mentioned, an independent sliding of the distal housing part  31  of the handling device  30  of the image transmission apparatus  11  with the shaft  20  on the one hand and of the proximal housing part of the handling device  30  on the other hand with respect to the visual field apparatus  61 . For this purpose, the housing parts  31 ,  32  of the handling device, the visual field apparatus  61  and the proximal sleeve part  70 , for example, contrary to the depiction in  FIG. 12  are configured in such a way that an axial sliding of the proximal sleeve part  70  with respect to the visual field apparatus  61  causes a displacement of the focal length and a rotation of the proximal sleeve part  70  with respect to the visual field apparatus  61  causes a displacement of the focus. 
     With visual field apparatuses  61  and image transmission apparatuses  11 , as presented above with reference to  FIGS. 1 through 12 —as already mentioned—the visual field can be modified by exchanging the visual field apparatus  61 . If the viewing direction is not parallel to the longitudinal axis of the visual field apparatus  61  and of the image transmission apparatus  11 , the viewing direction can be rotated on a conical mantle by rotating the visual field apparatus  61  around the longitudinal axis. In a few embodiments, the visual field apparatus  61  and image transmission apparatus  11  can be rotated independently of one another. In this case, by turning the image transmission apparatus  11 , the image recorded by a video camera can be turned, in particular set upright. The video camera here can be positioned on the distal or proximal end of the image transmission apparatus  11  or can be coupled with the proximal end of the image transmission apparatus. For example, in the embodiments presented above with reference to  FIGS. 1 and 2, 5 and 6, 11 and 12 , the recorded image, rather than by a rotation of the entire image transmission apparatus  11 , can be rotated by a rotation merely of the sensor carrier  43  or of the optical carrier  96  or of the prism device  98 . 
     Alternatively or simultaneously, the visual field apparatus  61  and the image transmission apparatus  11  can be configured in such a way that a rotation of the two relative to one another causes an axial sliding of one or more lenses. For this purpose, a thread, a helical groove or a helical stud, for example, is provided on the visual field apparatus  61  and an axial groove or axial stud on the image transmission apparatus  11 . A frame of the lens or lenses is engaged both with the thread, helical groove or helical stud on the visual field apparatus  61  and with the axial groove or axial stud on the image transmission apparatus  11 . Alternatively, the thread, the helical groove and/or helical stud are provided on the image transmission apparatus  11  and the axial groove and/or axial stud on the visual field apparatus  1 . It is also possible to have two threads or helical structures with opposite thread directions. 
     In the described cases, a relative rotation of the visual field apparatus  61  and of the image transmission apparatus  11  can cause an axial movement of the lens or lenses. Because of the axial movement of the lens or lenses, the focus and/or focal length and thus the size of the visual field can be modified. 
     Alternatively or simultaneously—as already described in part—a simple axial relative movement of the visual field apparatus  61  and image transmission apparatus  11  can cause a modification of the focus and/or focal length or the visual field. For this purpose, because of the relative movement, one or more lenses or a rod lens system or light-sensitive sensor can be slid relative to one another and/or to the object. The relative movement, for example—as already indicated—is generated by a rotation of the rotatable sleeve  71 , which is connected so that it can rotate, but not axially slide, with the proximal sleeve part  70 . Reciprocally engaging threads  68 ,  78  on the visual field apparatus  61  or on the rotatable sleeve  71  can cause a rotation of the rotatable sleeve  71  relative to the visual field apparatus  61  into an axial sliding of the visual field apparatus  61  relative to the proximal sleeve  71 , and here the image transmission apparatus  11  is connected in friction-locked or form-fitted manner with the proximal sleeve  71 . 
       FIG. 13  shows a schematic flow diagram of a method for providing an endoscope and for autoclaving a visual field apparatus. Although this method can also be executed with image transmission apparatuses—in particular, endoscopes—and visual field apparatuses, which differ from those presented above with reference to  FIGS. 1 through 12 , hereinafter reference numbers from  FIGS. 1 through 12  are used in order to facilitate understanding of the method. 
     In a first step  101 , a visual field required in a successive application is determined. In a second step  102 , a visual field apparatus  61  is selected with the determined visual field  90 . In a third step  103 , an image transmission apparatus  11  is combined or conducted together with the selected visual field apparatus  61 , in particular inserted into the channel  90  of the selected visual field apparatus  61 , in order to form an endoscope  10 . 
     The first step  101 , second step  102  and third step  103  form a method for providing an endoscope for a successive application of the endoscope, for example in a medical investigation or a medical procedure. 
     In a fourth step  104 , the endoscope provided by the first step  101 , second step  102  and third step  103  is used. After use of the endoscope  10 , in a fifth step  105  the image transmission apparatus  11  is removed from the visual field apparatus  61 . 
     After removal of the image transmission apparatus  11  in the fifth step  105 , in a sixth step  106  the channel  90  on the proximal end is closed in fluid-tight manner, for example by means of an insulating plug. In a seventh step  107 , the visual field apparatus  61  with the closed channel  90  is autoclaved. After autoclaving, in an eighth step  108  the channel  90  is opened. The sixth step  106  and eighth step  108  are not required when the optical apparatus on the distal end of the visual field apparatus, for example, as described above with reference to  FIG. 10 , is completely encapsulated or closed in fluid-tight manner in both the distal and proximal directions. 
     The sixth step  106 , seventh step  107  and eighth step  108  form a method for autoclaving the visual field apparatus. After autoclaving the visual field apparatus, an image transmission apparatus  11  can again be inserted into the visual field apparatus  61  in order to repeat the third step  103  and the following steps.