Real-time high-resolvance image correlation by Bragg diffraction in saturable absorbers

Real-time image correlation is achieved by coupling coherent Fourier spectra inside saturable absorbers. Previously described optical correlators using nonlinear susceptibilities are strongly limited by the angular selectivity of Bragg diffraction in thick interaction cells. These difficulties were overcome by a special 3-D arrangement of the interfering beams. High-quality quasi-real-time holographic images, enabling cross-correlation of photographic transparencies free of detection noise, are demonstrated.