DEPTH-OF-FOCUS ENHANCEMENT: Simple wavefront-coding setup is adjustable in real time

摘要

An optical technique called "wavefront coding," invented by Ed Dowski and Thomas Cathey at the University of Colorado (Boulder, CO) in the mid-1990s, provides a simple, effective way to increase depth of focus in many imaging systems. The technique has found commercial success and remains of interest to researchers. In wavefront coding, a contoured clear plate is placed at or near the pupil plane of an imaging system; the plate introduces a phase shift that varies cubically across the pupil. The system's resulting point-spread function (PSF) is relatively uniform both across the image plane and through an extended focal range. The plate degrades the PSF somewhat but does it uniformly across the aperture and through-focus; to get a good image, a computer calculation removes most of the degraded PSF effects.