激光热透镜效应及其等效焦距测量实验设计

Experimental design of laser-induced thermal lens effect and the measurement of its equivalent focal length

基于共轴双光束干涉法设计了激光热透镜效应及其等效焦距测量装置.使用厚度约为200μm的薄酱油层样品作为观察热透镜效应的介质,将其置于半导体激光器的汇聚点上,可以在光屏上观察到同心衍射圆环,定性演示激光热透镜效应,并对热透镜的等效焦距进行定量测量.实验结果显示:薄酱油层在半导体激光照射下产生的热透镜效应可等效为凹透镜;基于共轴双光束法的热透镜等效焦距测量较为准确,利用Origin软件对8组实验数据进行线性拟合,相关系数为0.997.

Based on the method of coaxial dual-beam interference,the laser-induced thermal lens effect and its equivalent focal length measurement devices were designed.A 200μm layer of soy sauce was used as the medium to be placed at the converging point of the semiconductor laser.Concentric diffraction rings were observed on the optical screen.This method could demonstrate the laser-induced thermal lens effect qualitatively and measure the equivalent focal length.The experimental results showed that the thermal lens effect of thin soy sauce layer under the semiconductor laser radiation was equivalent to a concave lens,and the equivalent focal length of the thermal lens could be measured accurately.The correlation coefficient was 0.997 obtained by fitting eight testing data with Origin software.