Since the award of several study contracts by Eglin Air Force Base, some designs have been reported. At the same session of the SPIE conference, other interesting examples of imaging spectrometers were described. They are summarized in this chapter to give a flavor of the kinds of instruments that have been designed and built. In a sense, this puts the meat of realization on the bones of theory.
18.1 The Westinghouse AOTF System
Eglin wisely chose several different approaches to obtain an imaging spectro-radiometer. Table 18.1 summarizes the properties of one example, based on an AOTF. SNR data in dB are given directly from the paper. There is always ambiguity in specifying an SNR in dB. The definition is either that dB=10log(ratio) or dB=20log(ratio) . I have assumed that they are dealing with a power ratio and used the first of the definitions, the more optimistic assumption. I then decreased the SNR by a factor of 10 to account for the factor of 100 difference in the required frame rate and that obtained by this AOTF. Their results are consistent with those calculated in Chap. 14. A TMA is a three-mirror anastigmat.
The acronym stands for Hyperspectral Digital Imagery Collection Experiment. The instrument is a pushbroom device with a prism spectrometer and an InSb detector array. It has been used by the Environmental Research Institute of Michigan for remote sensing applications. It is summarized in Table 18.2.
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