Step-Stare Image Gathering for High-Resolution Targeting

摘要

Built around two infrared cameras and a high-speed opto-mechanical pointing mechanism, the Infrared Eye attempts to mimic the human eye by superimposing a high-resolution narrow field of view (first camera) for target identification over a lower resolution wide field of view (second camera) for situation awareness. A high-performance opto-mechanical pointing system allows the narrow field to be positioned anywhere within the wider field providing the operator with fast access to points of interest without losing situation awareness. During the development of the Infrared Eye, we found that we could use the opto-mechanical pointing system to produce high-resolution, wide field of view images at very high speed. The pointing system rapidly moves the narrow field of view to take high-resolution images that can then be assembled into a mosaic in a dynamic fashion, taking into account the movements of the platform to optimize the selection of mosaic sub-images. By using the high-resolution narrow field images to fill the mosaic, a wide field of view can be covered with the same high resolution as the conventional narrow field images. As compared to the current Infrared Eye concept, the step-stare approach eliminates one of the two cameras for a lighter and more compact system, while increasing the resolution in the wide field of view coverage, which would be impossible using conventional cameras and optics as wide field and high resolution are mutually opposed trade-off parameters in an optical design. The wide field and high resolution obtained by the step-stare technique also brings the detection capability in the wide field to the same level as that obtained with a narrow field camera in a conventional FLIR system. Within its related R&D activities, DRDC Valcartier has demonstrated the possibility to fabricating wideband Risley prisms in both the MWIR and LWIR spectra, as well as narrower band prisms in the visible and near IR spectra for passive and active imaging.