Abstract

Two-beam adaptive phase demodulators are used for noncontact and non-invasive measurements of the small surface displacements produced by ultrasonic waves propagating in an object. As an example the setup of a two-wave mixing-based photorefractive demodulator is shown in figure 1. These devices are based on the illumination of the surface of the object by a probing laser, collection of the light scattered by the surface of the object and its mixing with a beam directly derived from the laser (the pump beam).

© 2002 Optical Society of America