Santa Barbara Research Center

Hughes Aircraft Company

Nevil Q Maassen

Timothy S Romano

Donald E Salzer

Leonard E Peck

Matthew M Skertic

Arthur A Eneim

Joseph L Hlava

Kenneth L Gustafson

A dewar (20) useful in rapidly cooling a sensor (28) supported thereon includes a bore tube assembly having a cylindrical dewar bore tube (22) with an end cap (24) at one end to close the bore tube (22). The bore tube assembly is cooled by directing a stream of coolant at the interior of the end cap (24). The sensor (28) is mounted directly to the exterior surface of the end cap (24). A cold shield (34) partially encloses the sensor (28). A cold shield support bracket (38) mounts the cold shield (34) to the cylindrical side walls of the dewar bore tube (22) at a mounting location (36) axially displaced from the end cap (24) and therefore less effectively cooled than the end cap (24), so that heat is extracted from the support bracket (38) and the cold shield (34) less rapidly than from the sensor (28). From an uncooled starting condition, the sensor (28) is cooled to its operating temperature, and the cold shield (34) is cooled to its operating temperature, in about the same time.

Rapid cooldown dewar

A radiation detector assembly (20) includes a radiation detector (2), a silicon readout device (3) coupled to the radiation detector, and a platform 13 for supporting from a first major surface (13a) the readout device and the radiation detector. A second major surface (13b) includes a boss (14) for coupling, via an active brazing operation, to a cryogenic cooler. The platform is monolithic structure comprised of aluminum nitride (AlN) and eliminates at least one adhesive joint found in the prior art. AlN is selected because of its inherent material properties including a higher thermal diffusivity, relative to typical ceramic materials, for providing a reduced cooldown time of the detector to cryogenic temperatures. AlN also has a 300K- 77K thermal contraction characteristic that closely matches that of the silicon readout device and a high modulus of elasticity, thereby reducing distortion of the readout device thus minimizing stresses on indium bump interconnects. AlN also has dielectric characteristics that permit thin film metalization of the surface (13a) for providing electrical signal distribution.

Quick cooldown/low distortion hybrid focal plane array platform for use

An infrared detector assembly (12) of the type used in munitions and night vision systems having an improved focal plane platform (10). The focal plane platform (10) includes an end-cap (32) made from tungsten. Adhesively bonded to end-cap (32) is a ceramic mounting board (34). Ceramic mounting board (34) further comprises gold trace pattern (50) for conducting electrical signals generated by hybrid detector (26) to external control electronics. The improved focal plane platform (10) provides a relatively distortion free, thermally stable mounting platform upon which detector (26) is secured. Premature thermal fatigue failure of the hybrid detector is thereby inhibited.

Low distortion focal plane platform

An infrared detector assembly (10) of the type used in munitions and night vision systems having an improved coldfinger assembly (42). Such detector assemblies (10) include a tubular coldfinger (22) which is surrounded by a vacuum and an end-cap (28) mounted to the coldfinger tube (22) to define a cold end (24) which supports the infrared detector array (30) and related components. In accordance with this invention, the coldfinger tube (22) is a thin-walled titanium cylinder and the end-cap (28) is made of tungsten. The components are metallurgically bonded at the cold end (24) by an active brazing alloy deposited during vacuum furnace brazing. The titanium coldfinger (22) provides the necessary bending stiffness to support cold end components. The tungsten end-cap (28) provides a low distortion, thermally stable focal-plane. The metallurgical bond (46) provides for a hermetic seal which inhibits structural distortion during brazing, and during cyclical cooling of the detector assembly (10).

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Goleta, CA, United States of America

Nevil Q Maassen