基于傅里叶变换相位提取法的激光回馈应力测量系统

高端玻璃的内部应力精确测量关系其所在系统的安全性和可靠性。本文提出一种基于激光回馈效应的应力测量方法,激光回馈系统由激光器和外部反射镜构成,待测样品放置在回馈外腔中,通过回馈光对激光器内部增益调制产生的偏振跳变现象提取双折射信息,进而获得应力。首先,从理论上分析了回馈系统中激光器输出的正交偏振模式相位与外腔应力双折射的关系;接着,通过傅里叶变换的方式得到双折射外腔激光回馈系统光强调谐曲线的相位信息;然后,采用标准四分之一波片对系统和算法的精度进行了测试。最后,采用激光回馈系统对不同的飞机座舱有机玻璃样品内应力进行了测量,并给出测量结果。实验结果表明:该系统对应力的条纹数测量精度优于8.3×10-4,满足高端玻璃的应力检测需求。

Laser feedback stress measurement system based on fourier transform phase extraction method

Accurate measurement of the internal stress in high-end glass relates to the safety and reliability of the system in which it is used. This paper proposes a stress measurement method based on the laser feedback effect. The laser feedback system consists of a laser and an external mirror. The sample to be measured is placed in the external cavity of the feedback system, and the polarization flipping of the laser induced by the gain modulation of feedback light is used to extract stress information. First, the relationship between the phase of the orthogonally polarized modes of the laser and the birefringence of the external cavity was theoretically analyzed. Next, the phase information of the orthogonally polarized tuning curve was obtained by Fourier transform. Then, the precision of the system and algorithm was tested using a standard quarter-wave plate. Finally, the laser feedback system was used to measure the internal stress in various aircraft cockpit plexiglass samples and measurement results are given. The experimental results show that the measurement accuracy of the system for fringe number is better than 8.3×10^-4, which meets the stress detection requirements of high-end glass.