基于二维光学相干层析的多层薄膜结构无损定量评价

为了实现对多层薄膜结构厚度进行快速准确的测量和无损定量评价,研制了二维光学相干层析(Optical Coherence Tomography,OCT)系统,避免了传统一维OCT系统逐点扫描导致成像效率低下的问题。阐述了去除OCT共轭镜像理论,采用了五步相移干涉法,具体由压电驱动器驱动参考镜实现,做到了对OCT共轭镜像的去除,避免出现OCT图像的混叠。所研制的OCT系统具有极高的系统分辨率和较好的信噪比,可以实现对手机钢化玻璃薄膜内部四层结构厚度(钢化玻璃、静电胶层1、防爆贴膜和静电胶层2)进行准确测量。实验结果表明:自研制的系统可快速高精度地对多层薄膜结构厚度进行测量,可以推荐使用在多层薄膜的无损定量评价中。

Quantitative nondestructive evaluation of multilayer thin films based on two-dimensional optical coherence tomography

In order to achieve fast accurate thickness measurement and nondestructive evaluation of multilayer thin films, a two-dimensional optical coherence tomography ( OCT) was developed. The developed system did not need to point-by-point scan the sample and therefore, the problem of low imaging efficiency was avoided by point by point scanning. In addition, the theory of removing OCT conjugate mirror image was presented;also, five-step phase-shifting interferometry method was employed the system to remove the effect of OCT conjugate mirror im-age and finally to avoid image aliasing. A PZT actuator was used to drive the reference mirror to achieve the five phase. By using the system, the internal structure of mobile toughened glass film was accurately measured, including toughened glass, the first electrostatic glue, explo-sion-proof film and the second electrostatic glue. Experimental results demonstrated that the home-made system had high-accuracy and high-speed imaging performance for the measurement of multilayer thin films. It could be recommended for non-destructive evaluation of multilayer thin films.