Spectral Characteristics Elaboration Technique for Wide-Aperture Acousto-Optical Tunable Filters

The construction of a wide-aperture acousto-optical tunable filter with a synthesized spectral characteristic is considered. The technical basis is a filter based on acoustic light diffraction, all the main characteristics of which are determined by the parameters of the phase volume diffraction grating created in a crystalline medium by an acoustic field generated by a piezoelectric emitter. The possibility of forming the transfer function (spectral characteristic) of an acousto-optical tunable filter by forming a control signal and creating an inhomogeneous dynamic phase diffraction grating in the medium is studied. It is shown that a single-coordinate model of acousto-optic interaction can be constructed using the wide-aperture acousto-optical filters used in modern hyperspectral systems. The relationship between the parameters of the control high-frequency signal, the acoustic wave creating the grating, and the spectral transmission function of the filter is determined. Fundamental limitations on the width of the spectral transmission window are formulated. The relations allow one to describe the operation of an acousto-optical filter with an arbitrary law of amplitude and frequency modulation of the control ultrasonic signal with a limited transmission coefficient. The results can be used in designing optical spectral systems with a controlled transmission function of an acousto-optical filter.