Anamorphic imaging spectrometer
Rand C. Swanson, Thomas S. Moon, Casey W. Smith, Michael R. Kehoe, Steven W. Brown, Keith R. Lykke · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2008
Deployment of compact hyperspectral imaging sensors on small UAVs has the potential of providing a cost-effective solution for rapid-response target detection and cueing based on time critical spectral information collected at low altitudes. To address this goal, a new compact hyperspectral imaging sensor is being developed with an anamorphic optical system that partially decouples image formation along both the spatial and spectral axes found in conventional push-broom hyperspectral imagers. This design concept benefits from a reduction in complexity over standard highperformance spectrometer optical designs while maintaining excellent aberration control and spatial and spectral distortion characteristics. The anamorphic optical system has the advantage of removing the spectrometer slit focus along the spatial axis and in turn eliminates nearly all aberrations in the front-end optics, regardless of field angle or aperture size. This paper presents results from the first prototype anamorphic imaging spectrometer, which weighs 4 pounds and is designed for operation in the Short Wave InfraRed (SWIR) spectral band over a wavelength range of 1 μm to 1.7 μm dictated by the uncooled InGaAs focal plane array used as the detector. The anamorphic system design will be discussed and results from characterization and field measurements will be presented.