Previous chapters presented several applications of speckle metrology that used a full-field and noncontact technique to measure displacements on the surface of an object. Other interferometric techniques include holography interferometry and moiré interferometry, both of which are outside the scope of this book.
Interferometric techniques usually require a coherent light source. Furthermore, measurements are normally performed in laboratories with isolated-vibration tables. Previous chapters provide solutions and improvements that bring these techniques outside the laboratory. The measurement procedure used in these techniques can generally be summarized by the following steps:
1. Recording a reference phase map;
2. Introducing the perturbation (phenomena to be measured);
3. Recording the deformed phase map;
4. Computing the difference phase map (fringe pattern);
5. Finally, phase processing is used to recover information about the
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