A temporally and spatially nonscanning imaging spectrometer is described in terms of computed-tomography concepts, specifically the central-slice theorem. The critical system element is a sequence of three transmission sinusoidal-phase gratings rotated in 60 degree increments which achieve dispersion in multiple directions and into multiple orders. The dispersed images of the system's field-stop are interpreted as 2D projections of a 3D (x, y, (lambda) ) object cube. Due to finite focal-plane array size, this computed-tomography imaging spectrometer (CTIS) is an example of a limited-view-angle tomographic system. The imaging spectrometer's point-spread-function is measured experimentally as a function of wavelength and position in the field-of-view. Reconstruction of the object cube is then achieved via the maximum-likelihood expectation-maximization algorithm under the assumption of a Poisson likelihood law. Experimental results using a spatial/spectral 'University of Arizona' target indicate that the instrument performs well in the case of broadband and narrowband emitters. A relationship between an object's spatial size and spectral resolution characteristic of limited-view-angle systems is demonstrated.

Date Published: 12 June 1995
PDF: 17 pages
Proc. SPIE 2480, Imaging Spectrometry, (12 June 1995); doi: 10.1117/12.210908

Published in SPIE Proceedings Vol. 2480:
Imaging Spectrometry
Michael R. Descour; Jonathan Martin Mooney; David L. Perry; Luanna R. Illing, Editor(s)