Dualband infrared focal plane arrays (FPA) were developed originally for multi-spectral imaging
applications, where their advantages in compactness and band-to-band pixel registration, relative to
conventional multispectral imagers, were recognized. As dualband FPA architecture is matured for
quantum well and mercury cadmium telluride focal plane arrays, and becomes within the grasp of
strained layer superlattice technology, applications in addition to multi-waveband imaging come to
mind. In various hyperspectral applications that employ gratings, the different grating orders can
sometimes be paired with the wavebands of the dual- (or multi-) waveband FPA, allowing high
efficiency hyperspectral imaging over very broad wavelength regions. Exploiting the "third dimension" of FPA detecting layers for dual- and multi-waveband capability proved its usefulness for
multi-waveband imaging; this paper will show similar advantages for hyperspectral applications and
describe such applications.
We describe a proof of concept for a snapshot dual-band visible hyperspectral imaging spectrometer. A commercially available digital camera was integrated into a computed tomographic imaging spectrometer to provide a means for this proof of concept. Two spatially coregistered data cubes covering the blue (400 to 500 nm) and red (600 to 700 nm) spectral regions were reconstructed and the results analyzed. We found that the system accurately reconstructs the spectral content of the scene and that the two data cubes are automatically spatially coregistered by virtue of the system design.
Recent advances in dual band infrared focal plane technology now enable the design and testing of a dual infrared band
snapshot imaging spectrometer, the first-ever of its kind. A review of proof of concept results from a dual-visible-band
Computed Tomographic Imaging Spectrometer (CTIS) system is presented. The dual-visible system demonstrates that it
is possible to reconstruct two spatially co-registered hyperspectral data cubes covering different spectral bands. Based
on the visible band CTIS proof of concept, a similar infrared system is now proposed. Critical to the CTIS system is the
design of the Computer Generated Holographic (CGH) disperser. Several different (CGH) designs are considered. A
first order optical design for the dual infrared band CTIS is presented.
A temporally and spatially non-scanning imaging spectrometer covering two separate spectral bands in the visible region using computed tomographic imaging techniques is described. The computed tomographic techniques allows for the construction of a three dimensional hyperspectral data cube (x, y, λ) from the two dimensional input in a single frame time. A computer generated holographic dispersive grating is used to disperse the incoming light into several diffraction orders on a focal plane composed of interwoven pixels independently sensitive to the two bands of interest. Separating the input of the two pixel types gives co-registered output between the two bands and overcomes the limitation of overlapping orders. The proof of concept in the visible is presented using a commercially available camera and the extension to the infrared is proposed.
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