超低损耗光学镜片(超镜)是构建高品质光学腔和进行许多光学测量的重要器件,对损耗在百万分之一水平的高质量镜片的测量是一个重要的课题。通过在扫描腔长的情况下调节腔的起振模式,然后在腔的TEM00模式附近扫描激光频率实现了注入激光和腔的TEM00模的有效匹配; 以迟滞比较电路触发下的光开关控制注入光场的方式获得了连续激光光腔衰荡信号; 实验中完成了同一批损耗在10-6量级的超高反射率镜片的批量测量．实测最高反射率镜片的反射率为(99.99914±0.00004)%,测量精度优于10-6．结果表明对于同一批相同工艺生产以及相同存储环境存放的超镜,其损耗也存在较大差异。

Ultra-low loss mirror (super-mirror) is an important optical element for high-quality optical cavity and optical sensitive measurements in many fields, and the measurement of mirror losses on 10-6 level is an important issue. We have effectively mode-matched the incident beam to the TEM00 mode of cavity by scanning cavity length and sweeping laser frequency near the TEM00 mode of cavity. An optical switch triggered by a hysteresis comparator was employed to cut off the incident laser beam and the cavity ring-down (CRD) signal was obtained. We have measured a batch of super-mirror with losses on 10-6 level. The precision of this system is better than 10-6, and the highest reflectivity is (99.99914±0.00004)% . The results indicate that the losses of super-mirrors are diverse even if the super-mirrors are from the same batch and stored in the same environment.