Displacement measurements over a square meter area using digital holographic interferometry

摘要

Current industrial demand for optical nondestructive testing includes the displacement analysis of large object areas. This paper reports on the use of a digital holographic interferometer to measure displacements over an area of 1.14 m~2. The object under study is a framed working table covered with a Formica layer fixed to a granite bench, and it is observed and illuminated employing a high speed and high resolution camera and a continuous wave high output power laser, respectively. A stabilization procedure needs to be established as long illumination distances are required in order to retrieve the entire surface optical phase during a series of continuous deformations. As a proof of principle, two different tests are presented: the first involves a slow continuous loading process and the second a vibration condition. The wrapped phase and displacement maps are both displayed.