We describe the achromatization of Wollaston prisms to reduce the angular dispersion in the splitting angle. Analytical theory and ray-tracing modeling is presented. In an example application, a sixfold reduction in dispersion is achieved for wavelengths in the region 400 nm to 1.7 μm. Experimental proof of concept is demonstrated, and in an example application, the spectral dispersion of extended images recorded through cascaded Wollaston prisms is shown to be reduced by an order of magnitude.

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Traditional hyperspectral imaging (HSI) sensors are inherently time-sequential during capture, relying upon scanning techniques to construct the resultant hypercube. This temporal constraint hence restricts the use of HSI to static scenes or platforms. The novel sensor outlined within this paper enables snapshot HSI. The Near-Infrared Image Replicating Imaging Spectrometer (N-IRIS) operates without any rejection in polarized light. This prototype has eight SWIR bands and a diagonal FoV of two degrees, with potential for sixteen bands in other infrared regions. Unlike other snapshot techniques, N-IRIS produces a spectral image directly without inversion. Many additional benefits include inherent compactness, robustness, no-moving-parts operation, lower processing overheads and resource needs. Dual polarimetricspectral imaging is also possible due to its inherent design, which offers additional discrimination and higher throughput.HSI algorithms for anomaly detection are prolific in variety, but almost none of them consider the temporal dimension, mainly due to current limitations on speed. This paper describes the results from advanced algorithms implemented on COTS hardware for video-rate operation and designed to exploit the temporal dimension. The synergy with N-IRIS has achieved anomaly detection within streaming HSI hypercubes at video frame-rates. Recorded datasets include static ground scenes with transient targets, while further AVRIS imagery achieved the video-rate detection of embedded simulated targets therein. This new capability through N-IRIS hence broadens the potential application and benefit of HSI sensors to dynamic or transient situations.

We have developed a new algorithm for the simultaneous retrieval of the atmospheric profiles (temperature, humidity, ozone and aerosol) and the surface reflectance from hyperspectral radiance measurements obtained from air/space-borne, hyperspectral imagers such as Hyperion EO-1. The new scheme, proposed here, consists of a fast radiative transfer code, based on empirical orthogonal functions (EOFs), in conjunction with a 1D-Var retrieval scheme. The inclusion of an 'exact' scattering code based on spherical harmonics, allows for an accurate treatment of Rayleigh scattering and scattering by aerosols, water droplets and ice-crystals, thus making it possible to also retrieve cloud and aerosol optical properties, although here we will concentrate on non-cloudy scenes. We successfully tested this new approach using hyperspectral images taken by Hyperion EO-1, an experimental pushbroom imaging spectrometer operated by NASA