A laser Doppler tomography method for investigating volume recording media

A laser Doppler tomography method is proposed for investigating scattering noises, shrinkage, modulation amplitudes of refractive index and absorption coefficient, and other characteristics of volume or thick recording media. The method is based on acoustooptical scanning of a test volume grating recorded earlier in the medium and on layer-by-layer collinear heterodyne detection of the scattered field. The optoelectronic scheme of the system intended for experimental validation of the method is considered. Formulas for estimating the spatial resolution of the method, the optimal test grating period, the maximal number of detected layers are obtained. Their dependence on the optical system grating parameters is shown. An example is reconstructed values of the amplitude and phase of scattered light in deep layers of a volume grating written in a photopolymer 130 µm thick.