Non-steady-state photo-EMF interferometer for detection of mechanical oscillations in transparent scattering objects.

The operation of an adaptive non-steady-state photo-electromagnetic field (EMF) sensor is studied in an interferometric arrangement including a diffuse scattering object-fiber optic plate. The mechanical oscillations of this plate induce the strains and stresses of the medium, which modulates the phase of the propagating light wave across the plate. The resonant frequencies of the mechanical system and the distribution of the phase modulation amplitude across the plate's surface are measured. The minimal detectable stress amplitude is estimated.

Visualization of oscillatory stresses in transparent media using a ß-Ga2O3 adaptive detector.

The phase-modulated optical signal produced by light propagation through stressed transparent media is detected using the non-steady-state photoelectromotive force technique. The mechanical system, including the glass plate and piezoelectric transducer, demonstrates resonant behavior in the vicinity of 100 kHz. The measured distribution of the optical phase is a bell-shaped surface for these frequencies. The simulation of the piezo-optic response shows qualitative coincidence with the experimental data and provides maps of the stress field. The characterization of the ß-Ga2O3 adaptive detector is performed for the light wavelength λ=532 nm.