Method for monitoring thermal stress change of high-reflection optical element under high-power laser irradiation in real time

The invention relates to a method for monitoring thermal stress change of a high-reflection optical element under high-power laser irradiation in real time, which comprises the following steps of: synchronously measuring cavity ring-down signals of S polarized light and P polarized light by adopting a polarized light cavity ring-down technology, and measuring ring-down time of the S polarized light and the P polarized light of the high-reflection optical element at multiple angles; the residual stress birefringence of the high-reflection optical element is obtained through program fitting, and then the thermal stress of the optical element under high-power laser irradiation is calculated. Under high-power laser irradiation, a high-reflection optical element causes temperature difference due to absorption of laser beam energy, and the temperature change and the nonuniformity of the high-reflection optical element in an optical material cause thermally induced birefringence through a stress optical effect, so t