Abstract: In a device for injecting the light energy of a laser beam into a multimode fibre-optic optical waveguide (2) a small part of the light emerging from the end face of the optical waveguide (2) is projected through a beam splitting cube (7) and a reproducing lens (21) onto a display screen (1), so that an image (24) of the end face of the optical waveguide (2) can be observed on the display screen (1). The arrangement is such that the system is correctly focused only when the distance between the optical waveguide (2) and a focusing point of the laser beam (12) reaches an intended value. The light spot of the laser beam on the end face of the optical waveguide (2) is clearly visible on the display screen (1) so than an optimum positioning and adjustment can be readily effected.

Abstract: An apparatus for precise, homogeneous and sharp-edged irradiation of a large area with the light of a laser beam (5), which can be used especially for large-area photodynamic therapy, is provided with a multimode fibre (10), which is illuminated by the laser beam by way of a microscope objective (4) and has a length of approximately 5 meters, and the end face (13) of which is imaged onto an irradiated area (7) of a working surface (6) by means of a microscope (17).