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.