This chapter presents the state of the art of the principal uncooled focal plane array technologies and the systems that employ them. All data are from current technical publications, rather than manufacturers' literature. Systems based on the three principal detection mechanisms are included (see Chapters 3, 4, and 5). The chapter concludes with a brief review of technical trends in the military and commercial markets for uncooled imagers and imaging radiometers.
Most modern resistive bolometer array technology derives from the pioneering efforts of a team under the direction of R. Andrew Wood at the Honeywell Technology Center that began in 1982. The basis was the following:
- It had been realized for twenty years that the key to bolometer performance was not the resistive material but the thermal isolation structure.
- Silicon micromachining technology, which was under development at Honeywell for low cost, low power sensors of various types, was an ideal technology for providing excellent thermal isolation structures.
- The U.S. Department of Defense, especially DARPA (Defense Advanced Research Projects Agency) and NVESD (U.S. Army Night Vision and Electronic Sensors Directorate) was a source of the many millions of dollars of funding and for technical guidance and military requirements definition, necessary for the full development of uncooled imaging array technology.
As a result, Honeywell Technology Center received military contracts beginning in 1985 which led to the successful development of an uncooled microbolometer array containing 336 columns x 240 rows of 50 x 50-Î¼m pixels operating at the U.S. TV frame rate of 30 Hz.
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