Infrared radiation passed through the field mask and spectral filters and was focused by the field lens onto the aperture defining the detector cavity entrance. The visible wavelength channels were similar to the infrared wavelength channels in construction, except that they used visible light filters, no field lens, and silicon diode detectors. Figure II.C.8 Focal plane array filter and lens components and configuration. The detailed optical system transmission, detector spectral response and overall relative spectral response for the four infrared bands are shown in Figs. II.C.9.a,b and are listed in Table II.C.5 .
Solid lines show the transmission of filters and lenses.
The calculations were based on illumination from a 2000 K blackbody for short wavelength leaks and a 200 K blackbody for long wavelength leaks. The origin of the discrepancy is not understood.