LASER-DOPPLER VELOCIMETRY WITH A COMPACT DISC PICKUP

A laser Doppler velocimeter employing a compact disc pickup for both f ringe projection and signal detection is described. The spectrum of th e recorded signal gives the information about the speed of the object. The device takes advantage of the Talbot effect to project the gratin g contained in the pickup onto a moving target,so that no imaging syst em is required. The peculiar imaging technique allows for the exploita tion of several optical configurations and permits the manipulation of the intensity profile of the projected grating. The instrument was us ed to measure the velocity of dust particles on a solid substrate in t he 1-m/s range but could also find an application to the study of liqu id flow. (C) 1998 Optical Society of America.