基于偏振可调谐激光器移频回馈的玻璃在线应力测量技术研究

High-end glass materials are applied in aerospace and precision optical systems. Their internal stresses affect material properties and system quality and have attracted attention in related fields of application. The existing technology is difficult to realize online, non-destructive stress measurement of glass materials. For this reason, this project proposes a frequency-shifting online stress measurement method based on polarization tunable laser feedback effect. The main contents and innovations include: (1) With fusion of semi-classical theory and polarization characteristics vector expansion model, a theoretical model for the helium-neon laser gain distribution based on the continuous tuning of polarization is established, the positioning method of complex distributed stress axes in the glass is studied; (2) Reveals the mechanism of polarization jump of the laser, the external cavity birefringence and intracavity frequency difference by the combination of F-P cavity three-mirror cavity model and orthogonal polarized laser principles, eliminates the blind area of the polarization jump phenomenon, so that the stress measurement range covers within half of the wavelength; (3) The glass to be measured acting as an external reflecting surface constructes a reflective birefringent external cavity feedback system with the laser, and multi-beam interference theory is combined to study the frequency shift feedback effect of multiple externally-reflected feedback to improve the measurement accuracy of the system. The project aims to research on-line optical stress measurement method and provide technical support for high-end glass producing and testing processes.

高端玻璃材料应用于航空航天及精密光学系统中，其内部应力影响材料性能和系统质量，已引起相关领域的重视。现有测量技术难以实现玻璃材料的在线无损应力测量，为此本项目提出一种基于偏振可调谐激光器的移频回馈在线应力测量方法，主要内容及创新点包括：.(1)融合半经典理论和极化特性矢量扩展模型,建立基于内腔偏振连续调谐的氦氖激光器增益分布理论模型，研究偏振可调谐激光器定位玻璃中复杂分布的应力主轴;(2)F-P腔三镜腔模型与正交偏振激光原理相结合，揭示激光回馈系统中激光器的偏振跳变与外腔双折射、内腔频差的作用机制，消除偏振跳变现象盲区，使应力测量范围覆盖半波长以内;(3)以待测应力玻璃为外部反射面，与激光器构建反射式双折射外腔回馈系统，结合多光束干涉理论，研究多重外回馈光重叠注入内腔的移频回馈效应，提高系统测量精度。旨在研究一种在线精确测量玻璃内应力的光学方法，为高端玻璃的加工及检测提供技术支撑。

高端玻璃材料应用于航空航天及精密光学系统中，其内部应力影响材料性能和系统质量。本项目提出一种基于偏振可调谐激光器的移频回馈在线应力测量方法，在前期激光回馈波片测量仪器的基础上，进行了为期三年的进一步深入研究，主要完成的研究内容和成果如下：验证了大频差激光器的偏振跳变盲区消除方案，揭示了内腔增大后对应力测量结果的影响；构建激光器谐振内腔-液体表面-外部反射光栅的四镜腔等效模型，提出基于双重外腔回馈效应的折射率测量方法，经实验验证测量精度达到5×10-5；设计了一种反射式激光回馈应力测量系统，能够满足大尺寸特种玻璃材料的在线应力测量需求，采用反射式激光回馈应力测试系统对航空座舱玻璃样品进行了测试，对于该样品的测量精度达到0.001MPa(力学结果与材料的应力-光学常数有关)。与国外主流的高精度应力测量仪器进行了比对，该系统可对标美国HINDS的单点扫描式应力测量仪。目前，随着特种玻璃在航天、航空、核技术、等特殊领域的需求，高精度、快速、高效测量是当前急需解决的问题。随着探测成像器件、数字图像处理技术的发展，本项目可进一步与全场测量方法相结合，实现高效率、高精度的全场材料应力测量。