Talbot interferometer based on a birefringence grating

Abstract

A 1-D coarse grating imaged onto a photorefractive Bi 12SiO 20 crystal is stored as modulation of birefringence. On this basis, the self-imaging phenomenon is implemented. When an analyzer is placed at the output of the crystal, the modulation of birefringence is converted into a modulation of transmission. In this case in the read-out process, self-images are generated and distributed along the propagation direction at those positions which coincide with the loci that the self-images occupy in case that an amplitude grating would be used instead of the combination of the birefringence grating and the analyzer. Moreover, it is demonstrated that by maintaining the read-out polarization state and the crystal configuration it is not necessary to convert the modulation of birefringence into a modulation of transmission to generate self-images. Its means that no matter the analyzer is removed, self-images are generated as well. In this case, the planes of highest visibility coincide with those planes corresponding to a conventional phase grating. It is well known that Talbot interferometers built in with ordinary gratings are not sensitive to polarization changes. On the other hand, it is showed that the birefringence grating stored in the crystal allows to implement a polarization sensitive interferometer. It means that if a birefringence material is tested, then the shifting introduced in the self-images can be used for quantitative determination of the material birefringence.