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 that becomes uniformly birefringent due to an external applied voltage is 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 is utilized. The ellipticity of the light exiting the crystal will be determined according to the local birefringence. Then, after passing through a polarizer, the coherent output will reproduce the incoherent input. In this way, under free propagation, coherent replicas of the grating will be obtained.