Abstract: For an interstitial thermotherapeutic treatment of biological tissue in which, for generating a coagulation necrosis, the radiation of the laser within a radiation period is guided into the tissue by way of a fiber optic waveguide, the laser power is reduced continuously or in steps during the radiation period.

Abstract: A method of treating benign prostatic hyperplasia employs the steps of inserting a diffusing light guide into a prostrate lobe and providing laser power to the diffusing light guide in order to necrose surrounding tissue. The diffusing light guide can be inserted into the central or lateral prostrate lobes by inserting a needle and a trocar transperineally into the middle of the lateral lobe, removing the trocar, inserting the diffusing light guide, and monitoring the position of the needle, trocar, and diffusing light guide using ultrasound. The diffusing light guide can also be inserted into the central or lateral prostrate lobes transurethrally and positioned with the aid of an urethroscope.

Abstract: An arthroscopic probe having an elongated shaft with a small probing hook, which can be used for diagnostic purposes and which, for therapeutic purposes, has a longitudinally displaceable optical fiber guided at the distal end of the probing hook so that it is curved by approximately 30.degree..

Abstract: A surgical laser instrument suitable for the alternate contant cutting and no-contact coagulating of biological tissue by means of a fiber-optically guided irradiation of a laser. Radiation which is emitted by the pyrolytic glowing of at least partially carbonized biological tissue, is received by the distal end of the fiber-optic light guide, guided back to a radiation detector, and is detected in a spectral region between 0.3 and 0.9 .mu.m, while the laser radiation is filtered out. The radiation output of the laser is controlled by means of the detector output signal, to a value under the destruction threshold of the fiber-optic light guide in such a manner that the radiation emitted during the burning of the biological tissue to be cut as well as of the tissue residues adhering to the distal end of the fiber-optic light guide and burnt into it, does not exceed a predetermined value.

Abstract: A shock wave generator for the fragmentation of concrements, having a light-pulse-transmiting light guide and a converter arranged at the distal light guide end and having an ionization surface which, when a light pulse impinges, initiates a shock wave in the surrounding fluid, as well as having a shock wave outlet zone. In order to increase its efficiency and durability, the generator is constructed such that the ionization surface extends obliquely sloped with respect to the beaming axis of the impinging light pulse and the shock wave outlet zone is arranged in the direct shock wave beaming area of the ionization surface, thereby permitting a largely unhindered, low-loss propagation for the shock wave to the application point.

Abstract: For the circumferential irradiation of objects, especially of vessels, hollow organs and solid tissue, by optical radiation of high intensity which is conducted via a flexible optical fiber, the optical radiation is coupled into the optical fiber at a predetermined angle (.beta..sub.1,.beta..sub.2) to the surface normal of the end face of the optical fiber such that it leaves the distant end of the optical fiber in the form of a conical surface.