Spectrally resolved detection of mixed acoustic vibrations by photorefractive interferometry

Abstract

Compact and fast response ultrasonic detection system by two-wave mixing in a gallium arsenide photorefractive crystal AIP Conf.

Defect Detection in Carbon Fiber-Reinforced Plate by Imaging of Mechanical Nonlinearity-Induced Sideband Vibrations

“…In Xiong et al [37], the use of a photorefractive interferometer in bandpass mode (PRI-BP) has been shown to have the potential to tackle the above problem. Photorefractive materials are a class of nonlinear optical materials whose refractive index is dependent on the local light intensity [49,50].…”

“…In PRI-BP (layout in Figure 12), the lowpass characteristic of the photorefractive crystal that causes the diffraction of the reference beam when mixed with the probe beam, combined with the use of a Pockels cell that modulates the optical phase of the reference beam at a frequency near to the one of a vibration frequency of interest (in casu: one of the sideband frequencies), results in a full-field vibrometry device with high selectivity to vibrations at the phase modulation frequency, and strong rejection of other vibration frequencies. The intensity of the diffracted reference beam in a PRI-BP is a function of phase modulations induced in the sample beam and in the reference beam and is given by [37].…”

“…𝐽 𝑛 (𝑥) is a n-th order Bessel function of the first kind The term 𝐽 0 (𝜖 𝑑𝑒𝑓𝑒𝑐𝑡,0 )𝐽 1 (𝜖 𝑑𝑒𝑓𝑒𝑐𝑡,0 ) ≈ 𝜖 𝑑𝑒𝑓𝑒𝑐𝑡,0 when 𝜖 𝑑𝑒𝑓𝑒𝑐𝑡,0 ≪ 𝜆 optical . The time-varying terms of interest having angular frequencies Ω (rad/s) The intensity of the diffracted reference beam in a PRI-BP is a function of phase modulations induced in the sample beam and in the reference beam and is given by [37].…”

“…Interestingly, in the first half of the 1990s, a full optical lock-in (or bandpass) camera based on a photorefractive interferometer was demonstrated [31][32][33][34][35][36] to be capable of real-time imaging of vibrations happening at a known frequency. The possibility of configuring a full-field photorefractive interferometer as an optical bandpass filter (PRI-BP) was also demonstrated for a scenario in which the sample was excited with multiple frequencies [37].…”

Determination of thermoelastic material properties by differential heterodyne detection of impulsive stimulated thermal scattering

“…In principle, the surface ripple induced by transient grating excitation can be locally detected by focusing a probe beam to a spot that is much smaller than the grating spacing. In that case, the local displacement leads to measurable deflection and optical phase change of the probe beam, which can be detected respectively by a knife edge [37,30] or an interferometer [38–40] approach. The feasibility of such approach depends on the smallness of the focal probe beam spot, which is diffraction limited.…”