Measurement of Surface-Displacements Normal to Line of Sight by Holo-Moire´ Interferometry

This paper describes a new technique called “Holo-moire´ interferometry” which combines the moire´ and holographic techniques so that full-field measurement of the displacements normal to the line of sight is achieved. The method is particularly useful in measuring in-plane displacements; a type of measurement for which the conventional moire´ technique is too insensitive, and for which holographic interferometry requires pointwise separation of displacement components from a multiple-hologram scheme. Holo-moire´ interferometry overcomes the major limitations of both. An example which compares experimental with analytical predictions is presented. The limitations of the scheme are discussed.