Аннотация:The paper presents results on theoretical and experimental investigation of a tunable acoustic-optic filter designed with the goals of applications in optics and spectroscopy for spectral filtration of divergent RI optical beams and images. Physical principles of operation of the wide-angular acousto-optic filter are examined and basic parameters of the developed instrument are described in the paper. The device was fabricated on base of a specially chosen crystal cut of optically anisotropic tellurium dioxide single crystal. Optimization of the filter parameters resulted in development of the instrument combining low driving power with high spatial and temporal resolution. Experimental block-scheme of filtration and optical setup for image processing are described in the report and some peculiarities of the imaging experiments in the middle IR region of spectrum are discussed in the paper