Measurement of transient out-of-plane displacement gradients in plates using double-pulsed subtraction TV shearography

Abstract

We report a technique for the measurement of transient outof-plane displacement gradients in plane objects by double-pulsed subtraction TV shearography. The fringe patterns are automatically and quantitatively analyzed by the Fourier transform method. A novel optical setup based on the separation and further recombination of illumination beams is demonstrated for the generation of carrier fringes. The principle of the proposed technique is theoretically described, and its immunity to environmental disturbances is discussed. Experimental results obtained with a metallic plate excited by the impact of a piezoelectric transducer are presented.

Shearography technology and applications: a review

“…This can be realized practically by translating a diverging lens within the illumination path but this can be difficult to achieve in dual-pulsed shearography where the separation of pulses can be as short as 1 μs. A solution to this problem was presented by Fernández et al [75]. In their configuration, shown in figure 14, dual pulses are generated from twin Nd:YAG laser cavities.…”

“…Reducing the aperture of an iris located at the front Figure 14. Carrier frequency generation in dual-pulsed shearography based on the source translation approach [75]. of the interferometer reduces the size of the spectral feature in frequency space as shown in figure 15(c).…”