光热干涉检测系统的实验参数选择

为了研究实验参数对光热干涉检测结果的影响,根据等厚干涉测量原理,利用赛德倾斜像差建立了相应的光热干涉测量模型.通过对探测光源的分析,利用随机函数建立一般性光源模型,定义了光源均匀度.在此基础上通过数值模拟,对不同光源均匀性下实验现象进行仿真,分析了光源均匀性对干涉测量结果的影响.分析表明,探测光源均匀性对热吸收干涉测量结果的影响可以忽略.同时还对比分析了不同探测器接受口径对测量结果的影响.结果显示,当探测器接收口径R=0.315cm时,在0～0.6λ的光热位移内光热信号呈单调下降,而且条纹对比度相对较大.通过曲线拟合得到在弱吸收情况下光热信号与光热位移的一个简单经验公式.

Experimental parameters choice of photo-thermal interferometric detection system

In order to study influence of experimental parameters on photo-thermal interferometric detection,according to interference principle of equal thickness,a theory model is set up by means of Seidel aberration of tilt. After various probe beams are investigated,a universal light model is proposed by means of random function,and uniformity of the light source is defined. Based on this model,it is simulated that interferometric experimental phenomena change with various probe beam,and the influence of probe's uniformity is analyzed on interferometric measurement,which show there are no difference among various probe beam. On the other hand,the influence of detector's aperture on interferometric measurement is analyzed. Results show it is the best when radius of detector's aperture is 0.315 cm. Under this condition,photo-thermal signal descends monotonously during fine scale photo-thermal displacement of 0～0.6λ,and the contrast of interferometric stripe is better. Under weak absorption,a simple experiential equation between photo-thermal signal and photo-thermal displacement can be concluded by curve fitting.