Spectrometric Imager

Abstract

Frequently one would like to know how an object appears, viewed at many different wavelengths. An optical device is described that encodes light from an extended object and focuses it onto a single detector in such a way as to provide information on both the spatial distribution of points on the object and the spectral distribution of light coming from each point on the object. The actual spatial and spectral properties of the object then are recovered by decoding the signals received by the detector. A mask pattern is described that is used in providing spatial information. It can be stepped cyclically to encode a two-dimensional pattern (intensity distribution of radiation). The pattern is simple compared to previously described masks. For an image resolved into, say, m × p spatial elements, the mask need only have (2m − 1)(2p − 1) encoding elements; this results in a considerable reduction in the cost of producing the mask. The device should have many applications, particularly in the field of satellite or space-probe surveillance. A modification of the instrument permits an analysis of the polarization of radiation in each spatial and spectral resolution element.