由于SU-8光刻胶的内应力将会影响高深宽比结构的全金属光栅的制作质量, 本文针对近年来SU-8光刻胶应力测量困难的情况, 提出了一种基于激光剪切散斑干涉技术的SU-8光刻胶应变分布测量的新方法。该方法通过对被测胶体加载前后两幅干涉图像的处理, 直接得到被测胶体结构的全场应变分布情况, 由胶体的应变变形数据即可反映出内应力的变化和分布趋势。同时使用ANSYS有限元分析软件对同一被测胶体进行应变仿真模拟研究, 获得胶体结构的变形场仿真数据。组建了实验系统, 进行了实验验证, 结果表明: 实际测量变形量约为1189 μm, 仿真的最大变形量为1088 μm, 测量误差在允许范围内, 且测量的形变趋势与仿真模拟结果相一致, 表明激光剪切散斑干涉技术可应用于SU-8光刻胶的应变分布全场无损检测。

The quality of full metal grating is affected by internal stress of SU-8 photoresist. Considering the stress measurement of SU-8 photoresist is difficult in recent years, the shearography is applied to measure the strain distribution of SU-8 photoresist which corresponds to the stress distribution of SU-8 photoresist. Strain distribution is acquired by processing interferometer images which are recorded before and after loading on the tested photoresist. The simulation result of the same photoresist is obtained by using the ANSYS finite element analysis software. The shearography measurement system is setup and demonstration experimental is carried out. The deformation of actual measurement is about 1189 μm, and the deformation of simulation is 1088 μm. The measurement error is in the allowed range. The deformation trend of experimental result is consistent with the simulation result. Results show that the shearography in SU-8 photoresist strain distribution measurement is valid and may be applied to measure whole field strain distribution of SU-8 photoresist in lossless.