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Scanning Infrared Instrument with Improved Sensitivity

IP.com Disclosure Number: IPCOM000087077D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Lukianoff, GV: AUTHOR [+2]

Abstract

In a scanning infrared instrument, the detection efficiency for infrared radiation is improved by incorporating a wavelength dispersive element, an array of individual detectors having different spectral sensitivities, and means of combining the outputs from these detectors to form a composite signal. Other elements of the instrument, e.g., the scanning system and display, need not be modified.

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Scanning Infrared Instrument with Improved Sensitivity

In a scanning infrared instrument, the detection efficiency for infrared radiation is improved by incorporating a wavelength dispersive element, an array of individual detectors having different spectral sensitivities, and means of combining the outputs from these detectors to form a composite signal. Other elements of the instrument, e.g., the scanning system and display, need not be modified.

The wavelength dispersive element may be a dichroic mirror if two detectors are sufficient. In that case the spectral reflectance of the dichroic mirror is tailored to divide the emitted spectrum optimally between the two detectors according to their spectral sensitivities (Fig. 1). If three or more detectors are needed to span the spectrum emitted by the specimen, the dispersive element may be a prism or diffraction grating. In that case the size and position of each detector is designed to intercept all of the dispersed radiation corresponding to its spectral sensitivity (Fig. 2). If the spectral sensitivities of two adjacent detectors overlap, their sizes and positions are chosen so that their contiguous edges occur at the position in the dispersed spectrum where their spectral sensitivities are equal.

For maximum sensitivity, the output signals from all of the detectors are added together by using, for example, an operational amplifier in a summing configuration.

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