Employing 532 nm Wavelength in a Laser Ultrasound Interferometer Based on Photorefractive Polymer Composites

Laser ultrasonic (LUS) receivers based on photorefractive (PR) materials are contactless and adaptive interferometers, which are used widely for materials characterization. Here, we present a simple LUS interferometer at 532 nm operating wavelength based on organic PR polymer composites (PVK/ECZ/C60) doped with the nonlinear chromophore 4-[4-(diethylamino)-2-hydroxybenzylideneamino] benzonitrile (Dc). A picoseconds laser at 1064 nm wavelength is used to generate ultrasound pulses in aluminum plates and by using this LUS polymer interferometer, detection of these ultrasound waves is remotely performed at the surface of the specimens. The LUS sensor is used to determine the thickness of aluminum plates about 0.25 mm, 3 mm and 10 mm. We also show the potential of this polymer receiver for detection of an artificial defect in a metal sample.