Study of transient deformations with pulsed TV holography: application to crack detection

Abstract

We report the measurement of reproducible transient deformations with single-pulsed-subtraction and double-pulsed-addition TV holography with both in-plane and out-of-plane optical configurations. An original synchronization system (controlling mechanical excitation of the object, firing the laser pulses, and image acquisition) used to obtain the subtraction and the addition correlation fringes is described. Experimental results are presented for the propagation of mechanical shock waves in a cantilever specimen and their subsequent diffraction by a crack in the specimen. These preliminary results show that the technique may be used for crack detection.

Comparison of carrier removal methods in the analysis of TV holography fringes by the Fourier transform method

“…Transient deformations can be qualitatively studied 16 with standard pulsed TVH. In a recent paper, we reported an improvement of a standard pulsed TVH system that enables quantitative measurements of transient bending waves to be performed.…”

Application of ESPI for the NDE of low-modulus materials using mechanical loading

“…Optical holography and Electronic Speckle Pattern Interferometry (ESPI) are emerging Non-Destructive Evaluation (NDE) methods which can be applied for the detection and measurement of displacement, strain, vibration, flow analysis, etc [1][2][3][4][5][6][7] . Because of the non-contact nature, these methods can be used for the detection of defects even in cryogenic conditions and corrosive environments.…”

Study of various preprocessing schemes and wavelet filters for speckle noise reduction in digital speckle pattern interferometric fringes

“…Time-average DSPI is a powerful tool for nondestructive evaluation of dynamic deformations. [1][2][3][4] But DSPI interferograms have inherent speckle noise. 1 The source of this noise is attributed to random interference between the coherent returns.…”