Hadamard transform imager and imaging spectrometer

An imager and a spectrometric imager, which achieve multiplexing by the use of binary optical encoding masks, have been built and tested. The masks are based on orthogonal, pseudorandom digital codes derived from Hadamard matrices. The spatial (and/or spectral) data are therefore obtained in the form of a Hadamard transform of the spatial (and/or spectral) scene; computer algorithms are used to decode the data and reconstruct images of the original scene. The hardware, algorithms processing and display facility are described. A number of spatial and spatial/spectral images, obtained in the laboratory, are presented. We present an analysis of the situations for which the multiplex advantage may be gained and of the limitations of the technique. Potential applications of the spectrometric imager are discussed. The spectrometric imager is covered by U.S. Patent 3,720,469 assigned to Spectral Imaging Inc., Concord, Mass.