Abstract: A hetero-contact solar cell has a front side provided for an incidence of solar radiation. The solar cell has an absorber of a crystalline semiconductor material of a first conductivity type, an amorphous semiconductor layer of the first conductivity type doped more highly than the absorber and an electrically conductive, transparent front side conduction layer provided on the amorphous semiconductor layer. A front side contact is provided on the solar cell and has spaced-apart contact structures. An emitter of a second conductivity type opposite to the first conductivity type is provided on a back side. A back side contact is arranged on the back side. The emitter-related absorption losses of the solar cells can be eliminated by the back side contact having a back side contact layer extending over the surface of the back side, and the front side conduction layer containing a specific resistance from 7×10?4 to 50×10?4 ?cm.

Abstract: An infrared radiation detector device has a cooled detector element (3) within a first optical device (internal cold shield (1.sub.i)). The first optical device includes a first diaphragm (6.sub.i) in front of said detector element. The infrared radiation detector device has a second optical device (external cold shield (1.sub.a)) which is thermally separated from the first optical device. The second optical device includes a second diaphragm (6.sub.a). The aperture (7.sub.a) of the diaphragm forms the pupil of the infrared optic which produces an infrared image on the surface of said detector element (3).

Abstract: In a multi-lens infrared objective with wide band chromatic correction, more particularly in the spectral range from 1.4 to 5 .mu.m silicon is employed as a material for lenses with a negative focal length. In this respect the lenses consist of materials, which as regards their dispersion curves are selected from three different material group, of which the first material group comprises materials, whose short wave absorption bands are relatively close to the shortest wavelength to be corrected, the second group comprises materials, whose long wave absorption bands are closer to the spectral range to be corrected than the short wave ones and the third group comprises materials, whose relative absorption band positions are between the materials of the first and second groups.

Abstract: The invention relates to an infrared objective (IR objective) with a lens arrangement for the production of an infrared image on a detector element of infrared detector equipment. In this respect it may be a question of a focal plane array (FPA) within a Dewar vessel with an internal cold shield for substantially preventing access of thermal radiation from the surroundings (spurious light fractions). The internal cold shield is placed behind an external uncooled cold shield comprising several staggered external cold diaphragms.

Abstract: A dioptric lens system comprises a plurality of lenses and a rear diaphragm functioning as an aperture diaphragm. An overall length in the order of the focal distance is obtained by the features that the object side surface of the object side lens comprises an aspherical component and that the intermediate and image side lenses are closely adjacent.