Adaptive photodetector based on nonsteady-state photo-EMF for the detection of elastic deformations and stresses

Detection of phase-modulated signals generated by mechanical oscillations of a transparent object (plane-parallel glass plate) is considered. The signal is measured with the aid of interferometric system that employs nonsteady-state photo-EMF in adaptive photodetector based on the $\beta$-Ga$_{2}$O$_{3}$ crystal. A mechanical system consisting of a glass plate and a piezoelectric transducer exhibits resonance at a frequency of about 100 kHz. The amplitude of phase modulation has a bell-shaped distribution over the plate surface in the frequency interval under study. The parameters of the adaptive photodetector are determined for a radiation wavelength of $\lambda$ = 532 nm.