Liu Feng, Gallais Laurent
Appl Opt. 2017 Nov 20;56(33):9225-9232. doi: 10.1364/AO.56.009225.
We evaluate and apply lock-in thermography as a method to quantitatively evaluate absorption losses of optical coatings. The principle of the method consists of applying periodically modulated laser intensity on the coatings and to monitor the periodic surface temperature evolution with an infrared camera. By application of a lock-in correlation procedure and using calibrated absorption samples, it is possible to obtain quantitative absorption values and to obtain absorption mappings with spatial resolution that depends on the optical configuration. Numerical simulations and experiments were performed in the case of 10-60 W laser irradiation at 1060 nm on different single layer coatings and highly reflective mirrors. In the tested conditions, the measurement of absorption down to 1 ppm level could be reached. The advantages, limitations, and potential applications of the technique are discussed.
我们评估并应用锁相热成像技术作为一种定量评估光学涂层吸收损耗的方法。该方法的原理包括在涂层上施加周期性调制的激光强度，并使用红外热像仪监测表面温度的周期性变化。通过应用锁相相关程序并使用校准过的吸收样品，可以获得定量的吸收值，并获得取决于光学配置的具有空间分辨率的吸收图谱。针对波长为1060nm、功率为10 - 60W的激光照射不同单层涂层和高反射镜的情况进行了数值模拟和实验。在测试条件下，能够实现低至1ppm水平的吸收测量。讨论了该技术的优点、局限性和潜在应用。
