Extending the range performance of diffraction limited imagers

Even the best thermal imagers available today achieve only a fraction of the range performance that is theoretically possible with a given objective lens. Diffraction from the finite aperture of a thermal camera reduces the contrast of high spatial frequencies as well as limiting the maximum spatial frequency in the image. Reclaiming the high frequency contrast can substantially extend range over what is normally thought of as diffraction limited performance. As explained in this paper, the requirements for achieving extended range are 1) small pitch large format focal planes, 2) deep charge well capacities, and 3) intensive deconvolution processing. We will call this combination PWP for pitch, well capacity, and processing which can theoretically increase range performance by a factor of 1.7 for an increase of 70%. In this paper, we also estimate the improved range performance that results from increasing the electron well capacity of long wave infrared cameras. The three technologies needed for a significant advance in thermal imaging are all available today: these include small pixel high density focal planes, deep wells or digital read outs, and digital processors. We hope this paper excites interest in combining those technologies to provide a significant advance in thermal imager performance.