Two-Dimensional LWIR Hyperspectral Filter Array

ABSTRACT:Spectral Sciences Inc. (SSI), in collaboration with Sandia National Laboratories (SNL), proposes a new approach to snapshot hyperspectral imaging (HSI), using a 2D array of Fabry-Perot cavity filters mated cooled, long-wave infrared (LWIR) focal plane array (FPA) pixels to produce three HSI dimensions (a hypercube) simultaneously in a compact, low weight and power package. Snapshot HSI sensors eliminate motion artifacts due to multi-frame collection, producing complete spectra and imagery in a single frame, undistorted by temporal lag times. They are especially suited for monitoring dynamic events, including moving vehicles, drones, gaseous plumes, and artillery firing. The hyperspectral data is obtained at the FPA frame rate. Combined with temporal algorithms, it can analyze spectral/temporal signatures. The proposed 2D array consists of superpixels, clusters of filters spanning the spectral band-pass, arrayed in an imaging format, a concept similar to the standard CMOS camera three-color Bayer filter. SNL demonstrated LWIR superpixel filter development under a program funded by the DoE Proliferation Detection Program Office, forming the basis for the proposed effort. SSI will investigate configurations of the filter bands and camera design that support operation of the highest spatial resolution, adaptively adjusted to the requirements of the user.BENEFIT:The successful project will produce the design and fabrication plan for a new LWIR hyperspectral filter to be used with a cooled MCT FPA to produce very high spectral resolution, good spatial resolution imagery. This revolutionary sensor will be compact, requiring no spectrally selective optical system; fast, producing full datacubes in a single frame; and sensitive, with high optical transmission and low noise. It will be particularly valuable for measurements of transient or dynamic events, where video or greater data rates are required. High data rate is compatible with temporal algorithms that extract signatures of engines, and clutter algorithms that extract spectral imagery in the presence of platform jitter or other sources of temporal interference. Consideration of spatial resolution will result in a sensor that can be adapted in hardware to higher spatial, lower spectral resolution operation at the users discretion. Military applications of the filter technology combined with an LWIR camera include, rifle and artillery muzzle flash detection, moving vehicle and drone tracking, and gaseous plume detection, especially in nighttime and high aerosol conditions where vis/SWIR sensors fail. Civilian applications include border and fence line security, home surveillance, environmental, effluent and hazardous chemical release monitoring, and industrial process monitoring.