UTILIZATION OF PHOTOREFRACTIVE CRYSTALS FOR HOLOGRAPHIC DOUBLE-EXPOSURE INTERFEROMETRY WITH NANOSECOND LASER-PULSES

A holographic double-exposure interferometer for deformation and vibra tion analysis of diffusely reflecting objects in quasi real-time is pr esented. Writing of holographic gratings with 3 ns laser pulses in pho torefractive sillenite-type crystals enables recording of sequences of double-exposure interferograms. A repetition rate of 12.5 Hz is achie ved with the set-up used. Automatic phase evaluation of the interferog rams is per-formed with a spatial-heterodyne technique. Photorefractiv e recording in a BTO:Cd crystal with pulsed illumination is investigat ed and discussed in view of the application in double-exposure interfe rometry. The performance of the interferometer is investigated by obse rving deformations of a vibrating test object. (C) 1998 Elsevier Scien ce B.V. All rights reserved.