Pphotorefractive materials; Two-beam coupling; Spatial amplification; Energy efficiency
A real-time image processing technique has been described, using a two-beam coupling geometry in photorefractive materials. An erase beam copropagating with the signal beam allows spatial amplification of selected frequency components at the Fourier plane. A single lens Fourier transformation and imaging has been employed here, making the scheme simple and compact. The technique is capable of performing operations such as edge enhancement, band pass filtering and pattern recognition, etc. It has inherent capabilities of real-time operation, cascadability and energy efficiency as compared to the conventional spatial filtering operations. Edge enhancement and band pass filtering operations have been demonstrated using a photorefractive BaTiO3 crystal for two-beam coupling.