Electronic speckle interferometry, phase-mapping, and nondestructive testing techniques applied to real-time, thermal loading

Deformation-phase measurement of diffuse objects that have started nonrepeatable dynamic deformation

We have developed what we believe is a new technique for obtaining a whole-field image representing the deforming amounts of a diffuse object. The object is supposedly continuously deforming and does not stop deforming during the measurement. This technique uses arccosine operations to extract the absolute, not signed, value of the phase. We assume that a right-phase change retains almost the same value in a small local area. This retention determines the sign of the phase and consequently the value of the phase change. The deformation phase during any term of the deforming process is shown as a map through the temporal-phase unwrapping of the calculated phase.

Noise-immune phase unwrapping by use of calculated wrap regions

We implement a proposed method for noise-immune phase unwrapping through the calculation of what may be called wrap regions. The theory of this method is reformulated and discussed with regard to random wrapping, a phenomenon that occurs with diffusely reflecting objects if the optical phase change caused by a deformation is calculated by subtraction of the phases calculated before and after the deformation. Two methods of eliminating random wrapping are presented. The algorithm for phase unwrapping is described, and experimental results are presented.

Deformation measurement with object-induced dynamic phase shifting

A simple, yet powerful, means of computing the phase of fringe patterns depicting dynamic phenomena is presented. It is shown that the basic principle of the phase-shifting methods can be extended to the case of dynamic situations. The crux is to recognize that the phenomenon under examination can itself provide the necessary incremental phase shifts. This new method possesses a very wide range of applications in the field of deformation measurement.