Analysis of Speckle Pattern Interferometry System

The ESPI measurement on an object is dependent on the direction in which the object is deformed. When the object is displaced or deformed in the direction normal to viewing direction, the phase of one beam increase, so that the relative phase of the two beams changes. When this change is a multiple of 2p, the speckle pattern remains the same, while elsewhere it changes. In this research field, this method is widely used to develop a new laboratory setup for implementing the speckle pattern interferometry. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given. In this project, an experimental setup of ESPI is proposed to analyze a stainless steel plate using 632.8nm (red) wavelength of lights.