Wavefront sensor for a scanning imager

Abstract

A wavefront sensor for use in a scanning imaging system for generating focused and defocused images of an object scene that is being imaged by the imaging system from a single input optical beam impinged thereon. The two images are combinable using phase diversity techniques for calculating the wavefront aberrations that are present in the imaging system. The wavefront sensor includes a first linear photodetector array for forming a best focused image of an object scene as an incoming optical beam scans across the first linear photodetector array. The wavefront sensor further includes a second photodetector array disposed parallel to the first photodetector array. The second photodetector array is provided with a compensator plate for inducing a known focus error in the image that is formed on the second photodetector array as the input optical scans across the second photodetector array. In one embodiment, the two photodetector arrays are configured as CCD arrays on a single substrate. In a second embodiment, each of the first and second photodetector arrays are configured as a plurality of spaced detector segments. The respective spaced detector segments of the first and second detector arrays are arranged in staggered relation and define regions of overlap therebetween. One or more of the regions of overlap associated with the second photodetector array include a compensator plate for inducing the known focus error.