The damage morphology information is crucially important for optical components to analysis laser-induced damage resistance. Because of complex configurations, some high-precision and high-resolution techniques have limitations to detect in-line damage sites. Thus, a modified lateral shearing interferometer is proposed to obtain three- dimensional damage morphology information. In the presented method, the original beam passing through damage sites is magnified by a microscope system, and separated by a parallel plate into two sub-beams. In the overlap region of the sub-beams, the interference pattern can be used to extract the damage morphology information. Systematic errors are also eliminated from obtained interferograms before and after pulse laser irradiation, respectively. Experimental results are presented to confirm the feasibility of the proposed lateral shearing interferometer for in-line damage morphology measurement.
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