Comprehensive framework for optimization of overlapping pixels in optically butted focal planes

Abstract

Very high-resolution space borne missions demand finer spatial sampling and larger swath coverage for several commercial and strategic applications including cartography, disaster monitoring, urban planning, and surveillance. To meet these contrasting requirements, optical sensors often employ optical butting techniques in their focal planes as this enables the usage of small format detectors instead of large format single detectors, thereby reducing fabrication costs. In the optical butting technique, small reflecting mirrors placed before the focal plane split the optical field into smaller segments, which are alternately imaged by individual small format detectors. A single continuous image is formed using the small image segments through image processing technique. This requires optimal overlaps among the image segments with adequate image quality in the common imaged region. Factors, such as the geometric alignment of detectors with the butting mirror edge, edge-vignetting effects causing modulation transfer function, and signal-to-noise ratio degradations in the overlapping regions, largely determine the achievable overlap and image quality in the optically butted focal planes. Our study presents a comprehensive framework for the optimization of overlapping pixels in the optically butted focal planes based on a quantitative multicriteria analytical approach. The proposed framework has been tested for various sensor configurations to establish its efficacy. Our study will enable the efficient design and development of high-performance focal plane assemblies for high-resolution optical sensors.