Infrared imaging spatial spectral interferometer for spaceborne rapid-response global surveillance

摘要

Abstract: We investigated the feasibility of infrared imaging Spatial Spectral Interferometers (SSI) for spaceborne rapid- response, global-surveillance. The SSI is a sparse aperture interferometer that uses subaperture phase modulation techniques and multispectral sensors to increase angular resolution while reducing weight, volume, and cost. The subaperture phase modulation technique and multispectral sensors augment the spatial frequency sampling provided by the sparse aperture entrance pupil. We developed image modeling codes for SSI sensors incorporating multispectral sensors, change detection, and image deconvolution methods. Due to time and computer resource limitations, we did not simulate SSI systems with subaperture phase modulation schemes. Using change detection, the SSI need not form a whole image, but only updates a previously obtained image (from airborne or low Earth orbit sensors). Using deconvolution, the SSI need not be held to optical tolerances - pathlength compensators and laser metrology maintain the approximate subaperture piston and tip/tilt. But, the SSI self corrects by imaging a point source to measure the actual point spread function. We estimated optical and mechanical performance of the SSI sensor. We have shown that SSI sensors benefit significantly from change detection methods and the deconvolution algorithms greatly enhance the spatial resolution of SSI sensors. We have shown that space based interferometric imaging for rapid-response, global-surveillance is a feasible concept and that SSI sensors show promise of supporting a near real time, high-resolution, Earth-viewing, spaceborne imaging system.!12