INTERFERENCE DEVICE FOR DISTANT REGISTRATION OF ACOUSTIC VIBRATIONS OF DIFFUSELY REFLECTING SURFACES Russian patent published in 1999 - IPC

FIELD: measurement technology, registration of vibrations of surfaces of object. SUBSTANCE: interference device for distant registration of acoustic vibrations of diffusely reflecting surfaces has coherent radiation source, beam splitter, two acoustooptical modulators, two generators of fixed frequencies f₁ and f₂ connected with outputs to inputs of proper modulators, phase detector, electric signal mixer connected with inputs to outputs of generators and with output to input of phase detector, photodetector, frequency selection unit connected with input to output of photodetector and with output to input of phase detector and optical forming system installed in path of rays. Radiation is split into two channels, measurement and heterodyne. Frequency of measurement channel is shifted through f₁ and that of heterodyne channel through f₂. Radiation of measurement channel diffusely reflected from tested surface is mixed with radiation of heterodyne channel. Interference signal with difference frequency Δf = f₁-f₂ is registered by photodetector. Signal from output of phase detector is proportional to displacement of tested surface. Invention makes it feasible to reduce noise level and to register poor optical signals with power of approximately (~10^-16Вт) W. EFFECT: registration of acoustic vibrations of surface of object at considerable distance without installation of reflector on it. 1 dwg