Abstract: A diode laser is disclosed that is self-pulsating without an increase in the starting current or a decrease in the efficiency. A special coating on an end face of the laser comprises in order a first mirror, a medium having an optical thickness which is at least substantially equal to an integer number of times half the wavelength of the generated electromagnetic radiation, and a second mirror. The coating comprises exclusively materials which have a higher bandgap value than that which corresponds to the wavelength of the generated radiation, while the reflectivities of the mirrors and the deviation of the optical thickness of the medium with respect to an integer number of times half the emission wavelength are chosen such that the group velocity dispersion (GVD) adjacent the wavelength of the generated electromagnetic radiation is negative, and preferably a minimum.

Abstract: A diode laser present in an gas or vacuum atmosphere. The semiconductor body of the diode laser comprises two end faces which bound the resonant cavity within which radiation is generated in an active region. The active region forms part of an active layer situated between two cladding layers on a substrate. At least one end face is coated with a covering layer. The covering layer comprises at least two sub-layers of a first dielectricum with a first refractive index and of a second dielectricum with a second refractive index, respectively, and the optical thicknesses and refractive indices of the sub-layers are chosen such that the maximum intensity of the field strength of the generated radiation in the semiconductor body and the covering layer lies outside the end face, and preferably such that the intensity of the field strength of the generated radiation is approximately a minimum adjacent the end face. Preferably, the covering layer comprises two or three sub-layers of dielectric materials such as Al.

Abstract: An exit section of an X-ray image intensifier tube, including an the exit phosphor screen, exit window and basic optical system, is optimized so as to achieve a high light yield, low optical aberration and a high resolution. The exit window notably has a pre-compensation geometry for curvature of the image plane of the basic optical system, or the exit window an interference filter, or the exit phosphor layer contains a layer of a comparatively slow phosphor in addition to a layer of a customary phosphor in order to achieve noise-suppressing image integration.

Abstract: A cathode ray tube, such as a projection cathode ray tube, having a multilayer interference filter disposed between the cathodoluminescent screen and the interior side of the faceplate, the interference filter comprising alternate layers having high (H) and low (L) refractive indices, the high refractive index material being niobium pentoxide and the low refractive index material being either silicon oxide or magnesium fluoride. These filters are substantially free from the crazing which occurs in known filters when subjected to the normal thermal processing of cathode ray tubes.

Abstract: An anti-reflection coating which comprises at least a three layer interference filter is evaporated on the external surface of a faceplate panel. The manufacture of the coating can be speeded-up substantially by selecting high and low refractive index materials which can be evaporated at ambient temperatures and subsequently hardened by high temperature annealing outside the evaporation apparatus. The annealing is carried out most conveniently during the standard processing of a cathode ray tube.

Abstract: On a support which supports a light-emitting semiconductor device there is arranged a cap which is hermetically sealed to the support. In the cap there is provided a transparent plate, an inner layer of which facing the semiconductor device consists of a material having a high refractive index (>1.7). On the outer side of the plate there is provided a layer of photosensitive lacquer which is exposed to the light emitted by the semiconductor device. After development of the layer of lacquer, only the exposed part which is situated opposite the semiconductor device remains. This part is heated to the melting point, thus forming a droplet of lacquer, after which the outer layer of the plate and the droplet of lacquer are removed by way of a non-selective etching method, so that a lens which is situated opposite the semiconductor device and a flat window which surrounds the lens are automatically formed at the same time.

Abstract: A monomode optical transmission fiber with a tapered end portion. A lens is arranged on the end portion. The lens has a refractive index higher than that of the fiber core. Such a fiber has a substantially better coupling efficiency from a diode laser into the fiber core. The lens can be formed by immersing the tapered end portion of the fiber in a transparent liquid material. The drop formed on the end portion of the fiber after withdrawal from the liquid solidifies into a lens.