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. We overcame these difficulties by a special 3-D arrangement of the interfering beams. High-quality quasi-real-time holographic images, enabling cross-correlationof photographic transparencies free of detection noise, are demonstrated.