Interferometry based on Lau effect with a grating registered in a photorefractive crystal

The use of a grating in the form of modulation of birefringence in a BSO cr ystal in a novel Lau interferometer set-up is proposed. The system behaves as a conventional Lau interferometer implemented by using two amplitude gra tings. Moreover, it permits control of the visibility and provides a contra st inversion of the interferometric fringes by rotating a polarizer. Two al ternative experimental arrangements with similar performance are presented. A theoretical approach is outlined and the predicted behavior is confirmed by results obtained under different experimental conditions. (C) 1999 Else vier Science Ltd. All rights reserved.