Electro-Optical Tests of CCD Imagers at the GEODSS ETS.

Abstract

As part of the GEODSS-CCD Technology Program, a series of three electro-optical tests of CCD Imagers was conducted on the GEODSS Experimental Test System (ETS) at Socorro. New Mexico. The tests were preliminary to establish the basis for developing and testing an advanced CCD automatic detection system which would provide Improved sensitivity and scan coverage rate for GEODSS applications.These preliminary tests resulted in the successful demonstration of STARE and Image-motlon-compensation (IMC) modes of operation, and provided a thorough evaluation and verification of present CCD system design models. Also, interesting electro-optical performance levels were demonstrated, compared with existing GEODSS system designs. As part of the GEODSS Program in the Space Surveillance Group, several projects are directed at the development of technologies which could lead to an automatic search and detection system for satellite surveillance, with improvements in sensitivity and high scan coverage rate. AtCESStONThis proposed system design is based on the unique features provided by charge-coupled-device (CCD) technologies for both optical imaging as well as video analog signal processing. The focal plain design for the proposed system incorporates a mosaic array of 25 to 30 CCD imager chips which are continuously scanned in the CCD Image-motion-compensation (IMC) mode with multiple measurements provided by several imagers on-focal-plane in the scan direction for MTI processing. CCD imager and processing chips are being developed by the Microelectronics Group in support of this technology program design. A preliminary measurements program is presently under way to determine the electro-optical characteristics of these CCD imagers in laboratory measurements, as well as camera field tests using existing telescopes at the GEODSS ETS. A. Site-Test ObjectivesThe overall objectives for the initial CCD camera site-tests were to evaluate the electrooptical, mechanical, and operational interfaces with the existing ETS sensors and to measure various aspects of CCD camera performance to allow a comparison with laboratory measurements and theoretical design predictions. Specifically, all interface requirements were to be satisfied and measurements taken on calibration stars and selected satellites to provide data on sensitivity, dynamic range, photo-responsivity, resolution, metric registration, acquisition capability for STARE and !MC, and effects of telescope dynamics for the IMC mode. The electrooptical experimental system and measurements were aimed at sensor characterization only. Although STARE and IMC modes were used and targets acquired, it was not intended or possible to conduct automatic searches with the existing imager electronic test system. B. Results SummaryAll site test objectives were achieved in this preliminary series of tests. Both STAREand IMC-mode operation were successfully demonstrated for the single-chip CCD camera. Over the total of the periods of testing; more than t00 measurement observations were a...