Userfriendly and Compact Holographic Camera Based on Photorefractive Crystals. Applications in high Accuracy Metrology

Abstract

Abstract. We present recent developments achieved in order to make compact and easy to handle a photorefractive holographic camera. The technological interest of photorefractive crystals as holographic recording medium will be shortly recalled. The reported improvement concerns the reduction of the optical head to some basic components (objective lenses, crystal and CCD camera) by use of optical fibers for light transportation. The new compact holographic head can be handled easily and placed in any position rendering this device more flexible and adaptable to any kind of problem. In addition, it offers the main advantage to make easier the interfacing with any kind of laser. Some applications are presented and show the versatility of the instrument as well as the quality of the results.

Video Ultrasonics by Pulsed TV Holography: A New Capability for Non-Destructive Testing of Shell Structures

“…In order to allow the comparison, at least one of the wavefronts is frozen and stored in a hologram by some appropriate temporal treatment of the illumination-recording process, and then reconstructed and superimposed to the other wavefronts. Apart from the classical and tedious photographic emulsions (Shiokawa et al 1975;Gagosz 1974, 78-83;Aleksoff 1974, 247-63;Vest 1979, 224-5 and 242-4;Henning and Mewes 1995;Fällströ m et al 1989), real-time recording media like thermoplastic film (Pohl et al 1992;Schroeder and Crostack 1996), bacteriorhodopsin (Blackshire et al 2002;Blackshire and Duncan 2004), or photorefractive crystals (Telschow et al 1999;Telschow et al 2003;Delaye et al 2000;Lemaire et al 2000) have been employed, allowing a much higher refreshing rate (up to tens of Hz for photorefractive media, although at the expense of a large light power demand). , also known as electronic speckle pattern interferometry (ESPI), use the image sensor of the video camera as a recording medium and employ a configuration of image hologram.…”