Abstract: A mushroom-shaped semiconductor stripe laser, particularly with transversal, monomode light distribution and a double heterostructure comprised of a substrate, a laser-active zone, a cover layer and an electrically contacting metal layer for the cover layer with the cover layer being underetched such that a mushroom-shaped structure is formed in which the laser-active zone is constricted to a stripe-shaped region. The ratio of the width of the cover layer to the width of the laser-active zone lies in a range between two and five, and the cover layer is electrically conductively connected with the metal layer on its outer surface as well as on at least one of its side surfaces.

Abstract: A semi-conductor laser comprising a crystal having a sequence of layers forming a heterostructure diode and which includes a laser active zone interposed between a pair of semiconductor layers. Each of these semi-conductor layers has a band gap which is greater than that of the layers within the laser active zone. The laser active zone includes a first semiconductor layer having a given band gap, and at least second and third semiconductor layers each having a band gap which is greater than that of the first layer. The first layer is contiguous with and interposed between semiconductor layers each having a band gap which is greater than that of said first layer and forms a pn-junction with one of those contiguous layers. A strip-shaped region of a uniform conductivity type diffused from the surface of the crystal penetrates into at least one layer of the laser active zone but does not penetrate into the first layer.

Abstract: Copolymers of methylacrylate/alkyl acrylate or methyl methacrylate/alkyl methacrylate are used as a binder for UV-sensitive recording materials, preferably recording materials which contain substances which are capable of discoloration.

Abstract: A radiation sensitive recording material contains a layer of a layer-forming substance and incorporated therein an organic halogen compound capable of producing hydrogenhalide when struck by high energy radiation, and a chromogenic arylvinyl pyran or arylvinylthio pyran which changes its color by reaction with hydrolide. The material provides records with high stability.