Reliability estimation of the precise measurement system for the high reflectivity of COIL mirrors

Using cavity ring-down spectrometer technique, the precise measurement system for the high reflectivity of COIL mirrors has been built. At the straight ring-down cavity condition, some factors that may affect the accuracy of the measurement system was estimated systematically. And the correspondent experiments were carried out too. The experiments results show that the high reflectivity of the COIL mirrors could be precisely measured by the measurement system with precision of 10－5. And the measurement results were accuracy and reliable under mode matching of test light and ring-down cavity.