Acousto-optic spatial frequency filter with minimal acoustic power consumption

Subject of study . The energy capabilities of acousto-optic Bragg diffraction in tangent geometry for the two-dimensional (2D) optical Fourier processing of optical images are investigated. Aim of study . The aim of this study is to develop an acousto-optic spatial frequency filter that provides maximum resolution with minimal acoustic power consumption. The filter is fabricated using a paratellurite (TeO 2 ) crystal. Method. The proposed method leverages the unique properties of TeO 2 crystals, in particular, their anomalously low acoustic wave velocity. To increase the resolution, Bragg diffraction at very low acoustic frequencies is employed. Diffraction at the minimum acoustic frequency is realized in a tangent geometry. This approach enables optimal 2D image filtering during optical Fourier processing. Consequently, two objectives—maximum filter resolution and optimal conditions for 2D optical image processing—are simultaneously achieved. Main results. An experimental prototype of an acousto-optic spatial frequency filter based on a TeO 2 crystal is developed for 2D image processing at an optical wavelength of 633 nm. A 2D image contour in the first diffraction order is experimentally obtained at an acoustic frequency of 9.9 MHz. Practical significance. The developed filter enables 2D image processing at a minimum acoustic frequency with minimal acoustic power consumption. The tangent-geometry-based acousto-optic diffraction enables the efficient processing of 2D images with maximum resolution.