On-line detection method based on optimal modified lateral shearing interferometry for evaluating the damage growth characteristics

The damage growth characteristic determines the lifetime of optical components and the operating costs of high power laser systems. Knowledge of the lateral size and the depth of damage sites are crucial to evaluate the subsequent growth. An on-line detection method based on optimal modified lateral shearing interferometry is proposed to simultaneously measure the lateral size and the depth of damage sites. Thus, the damage growth characteristics can be estimated more comprehensively and efficiently. In the presented method, critical parameters of the common-path configuration are analyzed and optimized to meet the measurement requirements. Experimental results are presented to confirm the feasibility of the proposed method for on-line measurement. The damage growth characteristics of an optical film under different fluences are also analyzed and discussed simply.