X1 2j 3 4 5 6 76910 15 20 25x

Wavelength (tan)

Fig. 9-16. Specific Detectivities and Operating Temperatures for Infrared Detectors.

(Courtesy of Santa Barbara Research Center.) The specific detectivity, D", Is a normalized figure of merit for the class of infrared detectors for which the noise (voltage or current) is proportional to the square root of the detector area and the electrical noise bandwidth. The values given vs. the wavelength show a sharp cut-off to higher wavelengths when the lower energy incident photons no longer generate sufficient charge carriers within the detector. Additionally, the operating mode (photo-voltaic or photo-conductive) and the operating temperature of the detector Is indicated. D'can be interpreted as the normalized inverse noise-equivalent power of the detector (with dimensions expressed as the square root of the detector area times the square root of the noise bandwidth divided by the noise-equivalent power).

TABLE 9-12. Characteristics of IR Detector Arrays with Read-out Electronics. The table shows detector characteristics based on material properties. (Source: Photonics Spectra, September, 1989.)
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