Using a novel computational imaging architecture, we double the field of view of a long-wave infrared microbolometer camera while maintaining resolution. Due to the compact designs enabled by this architecture and the critical impact of resolution on classification performance, this approach is compelling for surveillance applications where low size, weight, power and cost (SWaP-C) systems are desired. We detail the optical design, characterization, and performance of a compact, refractive, optically multiplexed imaging system for use in the long-wave infrared (8-12 μm). A pair of prisms are used to divide the aperture and expose the uncooled microbolometer focal plane to two fields of view simultaneously, doubling the number of output pixels and the horizontal field of view. The image is reconstructed by rotating the prisms about the optical axis, inducing opposing vertical shifts in the two channels. Focal length, field of view, MTF, and NEDT are used to compare performance to a conventional camera. Shifting methods for proper demultiplexing are discussed, and reconstructed images are offered as a demonstration of system performance.
A computed tomographic imaging spectrometer (CTIS) disperses the three-dimensional (3-D) datacube (x, y, λ) into two-dimensional (2-D) projections on a focal plane array (FPA). The 3-D datacube is subsequently reconstructed from these 2-D projections using iterative computed tomography algorithms. Conventional designs achieve the 3-D to 2-D mapping by incorporating an optimized disperser. However, these dispersers suffer from the linearity constraint inherent in the first-order grating equation. This constraint means that many of the FPA's pixels are either unilluminated or they are used to image redundant projections; in both cases, they can not be used to increase the datacube's spectral resolution. Here, we outline various hardware improvements that increase the CTIS's spectral resolution by making use of these previously unilluminated or redundant pixels. Specifically, we incorporated a new disperser based on a 2-D grating prism and a division of aperture approach. Included is an optical design analysis of the system, in addition to an experimental characterization of the instrument's performance. Lastly, the new disperser is compared to a conventional disperser to quantify the increased spectral resolution.
A computed tomographic imaging spectrometer (CTIS) is an instrument which can simultaneously obtain image spatial
and spectral information without moving parts in a single focal plane array integration time. When this instrument is
combined with a channeled spectropolarimeter, the instrument can also obtain complete Stokes polarization information
at each resolution element. The combined instrument, called a computed tomographic imaging channeled
spectropolarimeter (CTICS), has been developed in the visible wavelength region. This paper summarizes the CTICS
design and results obtained from data acquired during field testing of the CTICS instrument.
Two imaging systems have been designed and built to function as snapshot imaging spectropolarimeters; one system
made to operate in the visible part of the spectrum, the other for the long wavelength infrared, 8 to 12 microns. The
devices are based on computed tomographic imaging channeled spectropolarimetry (CTICS), a unique technology that
allows both the spectra and the polarization state for all of the wavelength bands in the spectra to be simultaneously
recorded from every spatial position in an image with a single integration period of the imaging system. The devices
contain no moving parts and require no scanning, allowing them to acquire data without the artifacts normally associated
with scanning spectropolarimeters. Details of the two imaging systems will be presented.
A computed tomography imaging channeled spectropolarimeter (CTICS) is a combination of a computed tomography
imaging spectrometer (CTIS) and a channeled spectropolarimeter (CHSP). The CTICS instrument can simultaneously
obtain image spatial and spectral information as well as polarization Stokes vectors at each resolution element in a single
focal plane array (FPA) integration time with no moving parts. An instrument has been designed and built for the
visible wavelength region at the University of Arizona. Performance testing is underway. In this work, we present
initial results from data acquired during testing of the CTICS instrument.
A Computed Tomography Imaging Spectrometer (CTIS) is an imaging spectrometer which can acquire a multi-spectral
data set in a single snapshot (one focal plane array integration time) with no moving parts. Currently, CTIS instruments
use a specially designed computer generated hologram (CGH) to disperse the light from a given spectral band into a
grid of diffraction orders. The capabilities of the CTIS instrument can be greatly improved by replacing the static CGH
dispersing element with a reconfigurable liquid crystal spatial light modulator. The liquid crystal spatial light modulator
is tuned electronically, enabling the CTIS to remain a non-scanning imaging spectrometer with no moving parts. The
ability to rapidly reconfigure the dispersing element of the CTIS allows the spectral and spatial resolution to change by
varying the number of diffraction orders, diffraction efficiency, etc. In this work, we present the initial results of using
a fully addressable, 2-D liquid crystal spatial light modulator as the dispersing element in a CTIS instrument.