Direct reconstruction methods for hyperspectral imaging with rotational spectrotomography

A new technique for hyperspectral imaging called spectrotomography collects all available photons and relies on computer tomography to reconstruct the three-dimensional data cube of an object. A rotational spectrotomographic (RST) imager is designed with a wide-aperture, objective-grating camera that is rotated in steps around its optical axis. The full range of spatial and spectral resolution is achieved by the use of a stepped-focal-length (zoom) lens to illuminate the grating. Two-dimensional projections of the object are analyzed with the use of both direct Fourier methods and filter-backprojection algorithms. The RST imager has applications to detection of optical emissions where large photon throughput is required.