Acousto-optic k-space Filtering of Optical Beams

Acousto-optic tunable filters (AOTFs) can be used for spatial filtering of optical beams. A noncollinear AOTF has a tunable ring-shaped transfer function determined by geometry of the refractive index surface in a uniaxial crystal. Different axially symmetric transfer functions can be synthesized using multi-frequency ultrasonic signals. In the report, theory of AOTF-based spatial filtering of optical beams is summarized. Specific transfer function of the AOTF - bandpass spatial frequency filter - enables hyperspectal phase imaging in dark-field mode using incoherent illumination. Operation of a dynamic ring-shaped optical trap based on the noncollinear AOTF is demonstrated.