Hughes Aircraft Company

Wallace W Chen

I-Fu Shih

An improved wide-spectrum test target assembly, with visual and near IR (infrared) targets integrated with a long wavelength emissivity target. A single relatively thick optical fiber (78) is used to receive target signals emitting from several thinner fibers (72, 74, 76), each carrying a signal of different wavelength. The integrated signal is then relayed to an aperture (108) of an emissivity target through a gradient index lens (88) to further combine with the long wavelength target signal emitted from the emissivity target assembly (100). By selecting appropriate numerical apertures and diameters of the fibers, relatively high power output is achieved. A light collimator (200) is also disclosed for collimating light generated by the test target assembly to simulate targets at infinity. The collimator includes a primary mirror (220) which is an off-axis section of a paraboloidal mirror, a secondary mirror (230) which is an off-axis section of a hyperboloidal mirror, and a support structure/baffle (210) which supports the mirrors in proper relation and also includes an integrated light baffle surface to prevent light from the test target assembly from passing directly to an image plane.

Integrated test target assembly and compact collimator

An improved target for testing and calibrating a detection device. The target (10) includes a metal substrate (12) with a first layer (14) of high emissivity material and a second layer (16) of low emissivity material are deposited thereon. In the specific implementation, the substrate (12) is copper, the first layer (14) is chromium-oxide and the second layer (16) is chrome. In the illustrative embodiment, an aperture (22) is drilled through the substrate (12) and the first and second layers (14, 16) thereon. An infrared emitter (20) is located at the aperture (22) to provide point source radiation. A conventional heater (26) is applied to the back surface of the target. A pattern is etched on second layer (16) on the front surface of the target using electron beam lithography. The use of a metal substrate (12) allows for the drilling of small holes more easily than in the conventional target. In addition, the metal substrate (12) provides good temperature uniformity without use of a separate metal plate due to the higher thermal conductivity of metal over glass. The elimination of the separate metal plate also simplifies target assembly and reduces target costs.

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La Palma, CA, United States of America

Wallace W Chen