高功率固体激光器运转状态下增益介质热效应实时在线测试技术

High power solid laser has important applications in material processing and scientific research due to its large output energy, high peak power, compact structure, easy for coupling and transmission, long life, mature technology of microstructure and other obvious advantages. However, high output power and high beam quality are difficult to achieve simultaneously limited by thermal effect of solid laser medium, which has become an important factor restricting the development of high power laser. The thermal effect in high power laser is one of the most important reasons for the deterioration of beam quality. It has been a critical problem that urgently need for further research, testing and solving..Because of the wide application requirements of solid laser, our group will focus our research emphasis on the real-time online testing technology of gain medium’s thermal effect during the operation of high power solid laser. Different from traditional off-line testing technology (interferometer), indirect wavefront sensing technology (Hartmann sensing) and thermal effect simulation technology, this project could realize the real-time online testing of gain medium during the operation of solid laser, correct the exiting simulation model with test data, and finally form a perfect thermal effect theory of gain medium in solid laser..Until now, a large amount of theoretical analysis about the thermal effect of the laser gain medium has been done at home and abroad, and some results have been obtained. However, there is no important breakthrough in the actual real-time online testing technology..This project aims at the research of gain medium real-time online testing technology during the operation of high power solid laser, and the key technologies about thermal distortion, including high precise online wavefront detection, phase matching, wavefront reconstruction, error analysis and control based on the analysis of the online testing principle and theory, finally forming a perfect theory system and testing method of laser gain medium real-time online testing..Our group also hopes to gradually establish a theory, method and platform of laser gain medium real-time online testing technology by the basic theory research and the breakthrough of key technologies in these years, to provide solid academic and technical support for demand in related fields at home and abroad.

高功率固体激光器运转过程中，增益介质的热效应对输出激光的光束质量和转换效率有着极为重要的影响。目前，国内外研究单位在热效应理论分析方面做了大量的研究工作，取得一定的研究成果，但在实时在线测试技术方面还没有形成重要突破。.本项目拟研究高功率固体激光器运转状态下增益介质热效应实时在线测试技术，通过对在线测试技术的基本原理及理论分析，深入研究热效应畸变的高精度在线波前探测技术、相位匹配技术、波前重构技术、误差及控制等关键技术，最终形成完善的激光器运转状态下增益介质热效应实时在线测试技术的理论体系，以及一整套完备的激光增益介质热效应实时在线测试方法。.区别于传统的离线测试技术（如干涉仪）、间接的波前传感测试技术（如哈特曼）、以及热效应模拟仿真等技术，本项目研究的技术能够实现激光器运转状态下增益介质热效应的实时在线测试，通过测试数据对已有仿真分析模型进行修正，最终形成完善的激光增益介质热效应理论。

研究高功率高效率高光束质量固体激光器热效应高精度在线测试技术、精确测试出激光器各增益介质在工作状态下的实际热效应，具有极为重要的意义和迫切的需求。.本项目的主要研究内容：热效应畸变高精度在线相位探测及重构技术、激光增益介质热效应测试精度及误差研究、激光增益介质热效应实时在线测试技术等。.本项目的主要研究成果包括：.系统研究了热效应畸变的高精度在线相位探测及重构技术（包括热效应畸变的高精度在线相位探测技术、噪声抑制与信号提取技术、相位在线匹配技术与相位解包裹技术、高精度在线相位重构技术等），建立了建立透射式和反射式实时在线测试模型及系统，实现了端面热畸变及晶体热效应畸变特性的在线测试。.针对激光增益介质热畸变在线测试问题，以固体激光器晶体波前热畸变为测量对象，研究基于透射式相位偏折测量技术的固体激光器波前畸变测试技术。采用非激光工作波长高密度点阵光源对增益介质均匀辐照，通过实时探测透射条纹的相位变化，获得激光器各个工作条件下的热畸变分布。同时，针对光学元件辐照热畸变，重点研究反射式波前测量、控制以及实际应用，构建性能可靠、稳定的反射式光束波前测量方法，通过对正弦条纹光强分布分析得出测量畸变相位，并进一步计算出热致波前畸变。系统综合测试结果表明，所提出的热畸变在线测试技术具有高精度、高实时性、抗环境干扰等突出优点。.通过对激光增益介质热效应测试精度及误差的深入研究，重点分析了影响测试精度的温度、振动等导致测试扰动等的因素，最后，在理论研究与仿真分析的基础上，完成了激光器运转状态下激光增益介质实时在线测试装置的构建以及测试技术的研究，形成了较为完善的激光增益介质热效应实时在线测试技术的理论体系，以及整套完备的激光增益介质热效应实时在线测试方法。.基于本项目的研究成果，能够充分掌握激光器的热效应特性，针对性的采用控制与改善方法，提高激光器性能，进一步推动激光技术的发展，从而促进高功率固体激光装置和高功率激光器的广泛应用。