Aperture and detector cavity considerations for wide and medium field-of-view radiometers

Design constraints regarding the ERBSS nonscanning radiometers are related to the necessity to exclude, as much as possible, unwanted radiation from the detectors. The usual approach to accomplish this is to provide an aperture which is both blackened and serrated on its interior surfaces. However, such an approach is not entirely satisfactory for a number of reasons. A somewhat different method to aperture design is, therefore, considered. This method minimizes the three sources of unwanted radiation and alleviates also the problem of aperture temperature variations. To achieve the potential accuracy of the considered type of radiometer, it is essential to design the cavity in such a way that any entering photon will experience at least five reflections before it is allowed to exit the radiometer. A number of feasible cavity configurations are considered.