Abstract: In this paper, the transient temperature distribution and subsequent the thermal distortion resulting of coated non-cooled optical components irradiated by an annular high power continuous wave (CW) laser beam are studied in detail. The thermal distortion of various coated noncooled optical components subjected to CW-COIL laser irradiation is tested by using a Twyman –Green interferometer and compared with theoretical results. It is shown that the experimental results agree well with the theoretical analysis.