RESUMO
One approach to flat sensor design is to use a lenslet array to form multiple subimages of a scene and then combine the subimages to recover a fully sampled image by using a superresolution algorithm. Previously, superresolution image assembly has been based on information derived from the observed scene. For lenslet arrays, we propose a new scene-independent approach based only on known imager properties in which relative subimage shifts are accurately estimated with a calibration procedure using point source imaging. Thus, the relative resolution enhancement provided by the scene-independent superresolution algorithm is impervious to changes in subimage content, contrast, sharpness, and noise.
RESUMO
Low-cost compact sensors for ultrasmall systems are a pressing need in many new applications. One potential solution is a shallow aspect ratio system using a lenslet array to form multiple undersampled subimages of a scene on a single focal plane array, where processing techniques then produce an upsampled restored image. We have investigated the optimization and theoretical limits of the performance of such arrays. We have built a hardware simulator and developed algorithms to process imagery similar to that of a full lenslet imaging sensor, which allowed us to quickly test optical components, algorithms, and complete system designs for future lenslet imaging systems.
RESUMO
A Brillouin-enhanced four-wave mixing phase conjugator featuring a field of view that varies by approximately an order of magnitude, i.e., from 2 to 20 mrad, is described. We control this variable field of view by utilizing a slightly noncollinear pumping geometry and by adjusting the pump-pump frequency difference to optimize the phase mismatch for the overall process. A model that describes the interplay between frequency and geometry to the Brillouin-enhanced four-wave-mixing phase mismatch is found to predict the expandable field of view.
RESUMO
We report what is to our knowledge the first demonstration of Brillouin-enhanced four-wave mixing over a long atmospheric path. Weak laser light reflected from a remote retroreflector was input to a high-gain conjugate mirror. The resulting amplified output returns to the retroreflector owing to its phase-conjugate nature. Despite atmospheric effects the phase-conjugate return energy measured at the retroreflector increased by a factor of 10(4) over the initial weak beam.
