Steinheil Optronik Gmbh

British Aerospace Public Limited Company

British Aerospace Plc

Matthias Erdmann

Karl Pietzsch

Johann Schweiger

Christoph Thoma

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).

Infrared objective

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.

Refractive broad band IR objective

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. In this respect the external cold shield is partly arranged in front of and/or partly within the lens arrangement, the external cold shield with the lens arrangement being so designed and so arranged in relation to the internal cold shield that each optical ray, which comes from the lens element and is outside the optical pupil, is reflected back via the external cold shield and the lens arrangement into the or, respectively, on the internal cold shield, one of the cold diaphragms constituting the aperture diaphragm. The infrared objective may be designed telecentrically. The infrared objective may be a component of a complex infrared optical system (for instance as a front afocal).

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.

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Munich, Germany

Matthias Erdmann