Hughes Aircraft Company

William M Rappoport

Edward F Zalewski

Carlo F LaFiandra

George R Huse

Peter Silverglate

A spacecraft telescope door (10) adapted for use with remote sensing devices requiring optical and infrared calibration. The door (10) includes a first calibration surface (24) disposed on a first panel (14) for providing a radiant temperature reference for infrared calibrations. A second calibration surface (26) is disposed on a second panel (12) for providing an absolute radiance reference for optical calibrations. A panel hinge (16) controls the relative position of the panels (12,14) with respect to each other, and an aperture hinge (20) controls the relative position of the panels with respect to the aperture (28). In a specific embodiment, the first surface (24) is painted with chemglaze Z306, a highly emissive paint with a low reflectance for facilitating infrared calibration. The second surface (26) is painted with YB71, a diffuse reflective paint for facilitating optical calibration. In the illustrative embodiment, the panel hinge (16) and the aperture hinge (20) are motorized for controlling the relative orientation of the panels (12,14) and the aperture (28). By controlling the orientation of the panels (12,14) and the aperture (28), the first surface (24) and the second surface (26) may be accurately positioned for infrared and optical calibrations respectively. In addition, the panels (12,14) may be positioned so as to protect the diffuse second surface (26) from ultraviolet degradation, as most white diffuse paints degrade with prolonged exposure to ultraviolet light. In addition, the first panel (24) may contain heaters and temperature sensors (25) for control of the radiant temperature.

Aperture door and calibration source for spacecraft remote sensing

A focal plane array employing a segmented multiplexer having differing unit cell capacitances and amplifiers in respective segments of the multiplexer. The segmented multiplexer accommodates and processes the maximum expected signal at differing illumination levels without saturation and provides for optimized noise levels in each of its segments. The focal plane array includes an array of detectors and an array of multiplexer cells respectively coupled thereto. The array of detectors comprises a plurality of groups of detector elements that each detect energy in a predetermined spectral region. The array of multiplexer cells comprise a plurality of groups of multiplexer cells that are respectively coupled to the plurality of groups of detector elements. Each multiplexer cell includes an integrating capacitor and an amplifier, and the integrating capacitor of each cell in a particular group has a predetermined capacitance whose charge integration capability corresponds to an expected maximum intensity level of radiation in the particular spectral region that is detected by the corresponding detector element in the detector array. The optimization of the characteristics of the integrating capacitor and amplifier provided for optimized detection of the radiation in that spectral region. By using more than one unit cell design, the response of each portion of the focal plane array is optimized to the range of expected intensities that will be incident on that portion of the focal plane array. In this manner, saturation is avoided in those portions of the focal plane that are expected to observe very high light intensities. In those portions of the focal plane that are expected to observe low light intensities, the cell amplifiers are designed to accommodate the lower intensity levels with decreased noise.

Growing community of inventors

Weston, CT, United States of America

William M Rappoport