Methodology for Obtaining Speckle Interferometry through Lateral and Angular Displacement

Interferometry is a highly useful tool in metrology, and speckle interferometry allows for measurements with micrometer-level resolution. In the following pages of this document, the standard technique or methodology will be presented to obtain interference fringes caused by lateral or angular displacement. That is, a diffractive element (such as a negative or photographic film) can be obtained by taking a double exposure photograph of an object in an initial position and then in a second position, thus causing a displacement. When this grating is illuminated with a laser beam and aided by an optical system, interference fringes can be observed on a screen. The position, thickness, and spacing of these fringes provide the necessary information to calculate the lateral or angular displacement.