矩形大口径激光光束质量评价光学系统设计

自适应光学校正技术可有效提升固体板条激光器的光束质量,但随着激光器输出功率的提升,输出光束口径逐渐增加,系统体积逐渐增大,自适应光学校正系统的设计难度也增加了。因此,在满足自适应光学校正系统中共轭探测等需求的前提下,统筹优化系统的尺寸参数,同时实现波前相位、光束质量评估等多参数的检测具有一定的研究意义。本文在系统整体尺寸为350 mm×180 mm×220 mm(长×宽×高)的条件下,研究实现了板条激光器输出160 mm×120 mm矩形光束多参数的检测。针对探测口径大、筒长限制、长出瞳距等技术要求,首先,利用双高斯初始结构的消像差特点,结合非球面技术,采用大倍率光束压缩后分光探测的设计方案,实现多参数的同时探测。其次,基于摄远成像和共轭成像等原理,确定系统初始参数。接着,建立仿真模型分析系统的成像质量和公差,为实验的搭建提供依据。最后,搭建实验平台验证设计结果。结果表明:所设计系统可在满足物像共轭、尺寸约束等条件下,实现对大口径矩形光束的共轭波前探测、光强均匀度检测和光束质量评估。实验测得被测光束β因子为1.24倍衍射极限,均匀度为73.8%,满足技术指标要求。

Design of optical system for quality evaluation of a large rectangular aperture laser beam

The adaptive optical correction technology can effectively improve the beam quality of solid slab lasers,but with the increase of laser output power,the output beam aperture and the system volume increase gradually,which make the design of adaptive optical correction system more difficult.Therefore,under the premise of meeting the requirements of conjugate detection in the adaptive optical correction system,it is of certain research significance to optimize the size parameters of the detection system as a whole,and realize the detection of multiple parameters such as wavefront phase and beam quality evaluation.In this paper,we realized the multi-parameter detection of 160 mm×120 mm rectangular beam emitted by slab laser under the condition that the overall size of the system is 350 mm×180 mm×220 mm(length×width×height).Accord-ing to the technical requirements of large detection apertures,limitation of tube length and long exit pupil dis-tance,firstly,the dual-Gaussian initial structure was used to eliminate the aberration.Combined with the as-pheric surface technology,the design scheme of splitting detection after high-ratio beam compression was ad-opted to realize the simultaneous detection and evaluation of multiple parameters.Secondly,the initial para-meters of the system were determined based on the principles of telephoto imaging and conjugate imaging.Thirdly,the simulation model of the detection system was established to analyze the imaging quality and the tolerance of the system,which were implemented to provide the basis for the construction of the experiment.Finally,the experiments were carried out to verify the design results.Results indicate that the conjugate wavefront detection,light intensity uniformity detection and beam quality evaluation of 160 mm×120 mm rectangular beam can be realized under the conditions of the object-image conjugation and size constraint conditions.In the experiment,theβfactor of the measured beam is 1.24 times the diffraction limit,and the uniformity is 73.8%,which meet the technical requirements.