SELF-IMAGING THROUGH INCOHERENT TO COHERENT CONVERSION

The self-imaging phenomenon is realized by utilizing an incoherent to coherent converter. For this purpose, a photorefractive BSO crystal th at becomes uniformly birefringent due to an external applied voltage i s employed. Then, an incoherently illuminated one-dimensional grating that locally modulates the induced birefringence is registered, In the readout process, a linearly polarized plane wave from a He-Ne laser i s utilized. The ellipticity of the light exiting the crystal will be d etermined according to the local birefringence. Then, after passing th rough a polarizer, the coherent output will reproduce the incoherent i nput. In this way, under free propagation, coherent replicas of the gr ating will be obtained. (C) 1996 Society of Photo-Optical Instrumentat ion Engineers.