Application part for an endoscope
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to an application part for use in either rigid or flexible endoscopes and having a viewing channel, and a working channel extending parallel to the viewing channel. The working channel is equipped with a guide as well as a defined stop for an insertable fiber optics waveguide which can be coupled to a laser light source. 
     A device of this nature is known, for example, from DEP No. 29 45 080. This device is used for endoscopic laser irradiation of urinary bladder tumors with the laser light emerging from the light waveguide being directed directly onto the tissue to be irradiated. The object of the present invention is to provide an application part for rigid or flexible endoscopes, with which fragmentation of concrements, such as bladder, urinary bladder, kidney or gall stones within living bodies, becomes possible. 
     The objective of the invention is achieved through an application part for flexible or rigid endoscopes wherein the working channel has an optics arrangement for concentrating the laser light emerging from the fiber optic wave guide onto a punctiform region and, further, the working channel extends beyond the optics arrangement toward the punctiform region to form a shock wave reflector. Moreover, a flushing channel is provided having an outlet opening which is at least partially directed toward the face of the optics arrangement. 
     A device for fragmenting a solid body is described in the earlier application No. P 35 06 249.5. This device, however, does not serve as an application part for a rigid or flexible endoscope. 
     The application part according to the invention can, for example, be either integrated into a rigid endoscope or placed onto a flexible endoscope. With an endoscope equipped in this way, bladder, urinary, kidney or gall bladder stones can be directly fragmented into extremely small fragments with shock waves, without the shock waves having to pass through the body, and with the stones under observation continuously throughout the procedure. The fragments can then be flushed out without problems or they can be passed naturally. 
     Below the invention is described in greater detail in conjunction with an embodiment represented schematically in the figures, in which 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal section along line I--I of FIG. 2 through the working channel of an application part for a rigid or flexible endoscope; 
     FIG. 2 represents a view from above onto the distal end of a device according to FIG. 1; 
     FIG. 3 is an enlarged view of the distal end of the application part of FIG. 1. 
    
    
     DETAILED DESCRIPTION 
     The application part shown in FIG. 1 consists essentially of a cylindrical part 1 with three channels extending parallel, of which one is a viewing channel 2, another a working channel 3, and the last a flushing channel 4. The working channel 3 has a guide 31 for a fiber optic waveguide 5, onto which a stop ring 6 is clamped or fastened with adhesive agents. The fiber optic waveguide 5 is slid into the working channel 3 until the stop ring 6 rests against a specially formed part 7 of the guide 31. In this manner, the position of the end face 8 of the fiber optic waveguide 5 within the working channel 3 is precisely defined. To prevent the sliding of the fiber optic waveguide 5 within the working channel 3, the latter is equipped with a clamping device 9. 
     The fiber optic waveguide 5 is connected at the inlet side with a laser light source known per se and therefore not illustrated. The laser light emerging from the end face 8 of the fiber optic waveguide 5 is bundled by an optics arrangement including lenses 10 to 14 onto a punctiform area 15. For this purpose, the optics arrangement is formed as a reduction optics arrangement with a reproduction ratio of 1:4 to 1:10, which reproduces the end face 8 in the region 15 correspondingly reduced. 
     The light intensity coupled into the waveguide 5 as well as the reproduction ratio of the optics are so adapted to each other that in the region 15 a so-called &#34;breakdown-effect&#34; occurs, as described in the above mentioned German patent application No. P 35 06 249.5 or in the dissertation by Dipl.-Phys. Jurgen Munschau &#34;Theoretische und experimentelle Untersuchungen zur Erzeugung, Ausbreitung and Anwendung laserinduzierter StoBwellen&#34; (&#34;Theoretical and experimental investigation concerning generation, diffusion and application of laser-induced shock waves.&#34;), TU Berlin, Berlin 1981. The shock wave generated by this &#34;breakdown-effect&#34; is focused by a spherical or elliptical shock wave reflector 16. When using a spherical reflector it is positioned such that the focus coincides with the focal point of the optics in region 15. When using an elliptical shock wave reflector with two focal points, one focal point coincides with the focal point of the optics in region 15, while the other focal point is directed onto the surface of the concrement to be fragmented. The illustrated embodiment has a spherical shock wave reflector and the area 15 lies on the plane defined by the outer border 17 of the shock wave reflector 16 in such a way that the endoscope can be placed directly onto the concrement to be fragmented. Thus, in each instance only fragments of the outer layer of the concrement are removed. This ensures that only extremely small fragments are generated, which can either be flushed out or passed by natural means. 
     Since the generated shock waves exert great stress on the optics, in particular on the lens 14, at least this lens 14 and, because of the high light intensities, possibly also the field lens 10 are made from quartz glass or sapphire. When shaping the lens 14 it is best if here a concave-convex lens is employed, with the curvature of the concave face corresponding approximately to that of the shock wave reflector 16. In this way, the lens 14 partially assumes the function of a shock wave reflector. Further, the lens 14 must be sealed gas and liquid-tight as well as shock-proof against the shock wave reflector 16 and the sealing material 18 must be made from a particularly elastic material. Silicon is an especially well suited material for this purpose. 
     Since during treatment the front lens 14 must be kept clean, the flushing channel 4 has at its distal end a bent nozzle 19, which directs a jet of flushing fluid directly onto the lens 14 (see FIG. 3). 
     With the currently available fiber optic waveguides and optics working channel diameters of 2 to 3 mm, the entire diameter of the application part, which is circular in cross section, is approximately 5 to 7 mm. The cross sectional area can be correspondingly reduced if the outer contour is even further adapted to the envelope 20 of channels 2, 3, and 4 (see FIG. 2).