Title :
Adaptive heterodyne photorefractive interferometer for ultrasound detection: optimization and application
Author :
Ing, R.K. ; Pouet, B.F. ; Krishnaswamy, S. ; Royer, D.
Author_Institution :
Lab. Ondes et Acoust., Paris VII Univ., France
Abstract :
The advantages of ultrasonic remote detection using a heterodyne photorefractive interferometer are demonstrated. The speckle nature of the light reflected by a rough surface (or after propagation through a multimode fiber) does not degrade the interferometer sensitivity. Thanks to the process of wave mixing in photorefractive crystals, this interferometer has a large etendue. Furthermore, the heterodyne detection provides an absolute measurement of the ultrasonic amplitudes. We investigate the influence of an applied ac electric field. Two photorefractive crystals, undoped BSO and BSO:Cr, which have different optical characteristics are compared. Finally, examples of application to NDE are demonstrated
Keywords :
bismuth compounds; chromium; light interferometers; light interferometry; multiwave mixing; photorefractive effect; photorefractive materials; remote sensing; speckle; ultrasonic materials testing; BSO:Cr; Bi12SiO20:Cr; Bi12SiO20:Cr; adaptive heterodyne photorefractive interferometer; applied alternating current electric field; heterodyne detection; interferometer sensitivity; light; multimode fiber; optical characteristics; photorefractive crystals; propagation; rough surface; speckle nature; ultrasonic amplitudes; ultrasonic remote detection; undoped BSO; wave mixing; Crystals; Optical interferometry; Optical propagation; Optical surface waves; Photorefractive effect; Photorefractive materials; Rough surfaces; Speckle; Surface roughness; Ultrasonic imaging;
Conference_Titel :
Ultrasonics Symposium, 1997. Proceedings., 1997 IEEE
Conference_Location :
Toronto, Ont.
Print_ISBN :
0-7803-4153-8
DOI :
10.1109/ULTSYM.1997.663096
