Acousto-optic image processing

Abstract

Acousto-optic processing of images is based on the angular selectivity of acousto-optic interaction resulting in spatial filtration of the image spectrum. We present recent theoretical and experimental investigations carried out in this field. Much attention is given to the analysis of the acousto-optic cell transfer function form depending on the crystal cut, the geometry of acousto-optic interaction, and the ultrasound frequency. Computer simulation results of the two-dimensional acousto-optic spatial filtration of some elementary images are presented. A new method of phase object visualization is suggested and examined that makes it possible to separate amplitude and phase information contained in an optical image. The potentialities of the acousto-optic image processing are experimentally demonstrated by examples of edge enhancement and optical wavefront visualization effects.

Image aberrations caused by light diffraction via ultrasonic waves in uniaxial crystals

“…Patterns of the transfer function TΔθ 1 ; Δθ 2 for collinear diffraction (Fig. 8a) coincide with the results obtained in [18]. It should be underlined that in this paper, the transfer function for the extreme AO interaction (Fig.…”

Angular resolution in acousto-optic image filtering

“…Image transfer through an acousto-optic (AO) cell was investigated experimentally and theoretically in a number of studies [4][5][6][7][8][9][10][11][12][13]. It was suggested in some publications that the main reason for deterioration of the angular resolution is acoustic-beam divergence (for example, when filtering collimated beams of white light [6,7] and strongly divergent laser (monochromatic) beams [9,12]).…”

“…It was suggested in some publications that the main reason for deterioration of the angular resolution is acoustic-beam divergence (for example, when filtering collimated beams of white light [6,7] and strongly divergent laser (monochromatic) beams [9,12]). …”

Beam deformation within an acousto-optic lens

“…Because of the selectivity of the optical spatial frequencies of acousto-optic devices, the diffraction beam of AOD2 will be seriously deformed [7,8]. However, the current RAMP research mainly focuses on the problem of the chromatic dispersion [9,10], while the deformation caused by the high sensitivity of light divergence is ignored.…”

“…Considering that the acousto-optic interaction belongs to strong interaction, according to coupled modes theory, the spatial frequency transfer function of AOD is as follows [7]:…”