Radiant energy – Infrared-to-visible imaging – Including detector array
Reexamination Certificate
1986-07-31
2001-02-27
Buczinski, Stephen C. (Department: 3662)
Radiant energy
Infrared-to-visible imaging
Including detector array
C250S352000, C257S443000, C257S447000
Reexamination Certificate
active
06194721
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is in the field of systems for presenting visable images of far-infrared scenes, and is particularly concerned with an uncooled imaging transducer for converting a far-infrared image to a visible or near-infrared image. There are various systems known for providing visible or near-infrared images of far-infrared scenes; these systems include both thermal and quantum types of detectors, each with its own advantages. Unfortunately, all of these systems suffer from one or more significant disadvantage. Specifically, for a thermal detector, only a very small percentage of the incident radiation is actually used to advantage in producing a visible image; the majority of the radiation is essentially dumped into a heat sink because of poor thermal isolation between the detector elements and their support substrate. In the case of a quantum detector, cryogenic cooling is usually required for efficient operation in the far-infrared. Thermal detectors, beside having the problem of poor thermal isolation (which degrades sensitivity), also have large thermal masses (which lengthen time responses). The instant invention is uncooled, and because of its construction, has detector elements with greater thermal isolation (which gives greater sensitivity) than known thermal systems, and less thermal mass (which gives a faster time response) than such known thermal systems.
SUMMARY OF THE INVENTION
This invention is an uncooled system for converting a far-infrared image to a visible image or near-infrared image. The system includes a transducer onto one side of which a far-infrared image is directed, and which provides either a visible image or a near-infrared image on the opposite side. The transducer includes a planar array of far-infrared absorbing islands on a thin-film support. The film is supported by a perforated plate, with the perforations centered on the islands. There is, on the opposite side of the plate from the film, a perforated shield in registration with the islands, and a partially-reflective sheet. The spacing between the sheet and the islands is such that far-infrared absorption in the islands is enhanced. The sheet is supported by a relatively thick and (visible light or near-infrared) transparent substrate. The bottoms of the islands on the film and the partially-reflective sheet together form a Fabry-Perot cavity for visible or near-infrared radiation directed through the substrate, whereby an image may be viewed or detected. An alternate embodiment of the invention additionally includes thin conductors connected to the islands and to one pole of a voltage source, with the other pole of the source connected to either (or both) the shield or the partially-reflective sheet. This voltage induces a force to bias the islands toward the substrate.
REFERENCES:
patent: 3603794 (1971-09-01), Mast
patent: 3967121 (1976-06-01), Redman
patent: 4272164 (1981-06-01), Trussell, Jr.
patent: 4441791 (1984-04-01), Hornbeck
patent: 4494826 (1985-01-01), Smith
patent: 4497544 (1985-02-01), Mitchell et al.
Buczinski Stephen C.
Dunn Aubrey J.
Gibson Robert P.
Harwell Max L.
The United States of America as represented by the Secretary of
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