Analytic expression of horizon imaging on infrared focal planearray in panoramic electro-optical tracker

Since the external disturbance may lead that horizon image formed on IR FPA plane in a panoramic optoelectronic tracker not parallel to the image projected on the focal plane array on the reflector pitching axis, a five degrees of freedom mathematic model for the panoramic electro-optical tracking system was established. The equation for horizon incidence plane was reconstructed, which included target information regenerated in geodetic rectangular coordinates. The subsequent analytic expression for the reconstructed horizon catoptric-dioptric image in IRFPA plane was obtained. The analytical expression can be used to compensate the elevation and roll disturbances when the target is detectable and the horizon is undetectable.