Optical techniques that measure displacements: A review of the basic principles

Abstract

There are a number of optical techniques that can be used to measure displacements on surfaces utilizing electromagnetic radiation. Moiré, holography, speckle interferometry speckle photography, developed separately in the range of visible light. These techniques make it feasible is to find displacements fields and through displacements get the necessary information to compute strain tensors. Concurrently all the above mentioned optical techniques are used to perform metrological measurements on surfaces both on light reflecting and light diffusing conditions, and slopes on reflecting surfaces. In this paper taking a very general approach, these techniques are presented as a body of scientific and technological knowledge that has basic components that are common to all of them.