Abstract

Acquisition of directional derivatives, invaluable in edge detection and edge enhancement, is tradition ally accomplished by use of various digital filtering techniques. These techniques in variably constitute high-pass spatial filters, making them noise sensitive. Attempts to suppress noise, e.g., by low-pass filtering, increase computation and compromise spatial resolution. An optical scanning technique for directly acquiring various spatial derivatives of two dimensional images is described. The technique employs spatiotemporal modulation of a focused scan beam, in conjunction with synchronous electrical detection, to acquire directional derivative information in a relatively noise-free fashion. The technique also allows spatial resolution to be electronically controlled in a dynamic fashion. Proof-of-principle results are presented. We also discuss an extension of this technique to tracking and identifying moving objects.

© 1992 Optical Society of America