Compensation Techniques in Speckle Interferometry

摘要

Anomalies in fringes pattern due to weak defect remain practically hidden when the object is subjected to load in between exposures. Increased load results in more number of fringes. In order to bring out the defective region vividly some procedure to reduce the number of undesired fringes should be adopted. Comparative speckle interferometry compares the response of the test object with that of the master object and the fringe pattern corresponds to the defect when the objects are identically loaded. Surface contours can also be compared. Use of phase shifting in comparative speckle interferometry would give the quantitative estimate of the residual difference.