板条固体激光器光束整形扩束系统设计研究

发布时间：2018-06-18 06:33

本文选题：矩形光束 + 光束整形　；参考：《中国科学院研究生院（光电技术研究所）》2015年硕士论文

【摘要】：近年来,通过不断研究,板条激光器正一步一步在高功率、高光束质量的道路上发展前进,然而板条激光器的几何对称结构和Zigzag光路设计虽然在理论上有望解固体激光器的热退偏,热致聚焦等热效应问题,但实验结果却远远没有达到理论的预期。多模输出、失调、动态畸变、泵浦增益不均匀等因素共同导致了板条激光器输出无论是输出功率还是光束质量都没有达到理论计算的结果。此外。板条激光器输出的是具有大长宽比的矩形光束,其非轴对称光强分布限制了这一类激光器的应用。其输出光束带有输出光束带有离焦与像散的波前畸变,其长方向与窄方向光束发散角不同,造成了聚焦光斑弥散、远场能量集中度降低,从而引起光束质量下降。为解决以上问题,本文设计了一套针对板条激光器出射光束的光学整形扩束系统,并对其做了仿真分析与实验验证。考虑到板条激光器输出光束是矩形光束,对其输出光束长方向与窄方向进行了能量分布分析后得到其窄方向光束能量分布为类高斯分布,长方向光束能量分布为超高斯-平顶分布,由此在Zemax中对板条激光器输出光束进行了仿真模拟,为后续优化整形扩束系统奠定基础。对几种典型的光束整形方法其各自优势与缺点做出了对比分析,综合考虑后提出利用柱面透镜与球面透镜作为元件设计整形扩束系统的思路。本文设计的整形扩束系统对入射光束宽度与发散角具有一定的动态范围,是一种介于针对单一参数设计的被动整形补偿系统与主动光学整形系统之间的半自动光学整形系统。对于需要加自适应光学系统进行进一步光束净化的实验来说,板条激光器出射的矩形光束经过本课题设计的光束整形扩束系统后的出射光束为方形光束,增大了光束在波前校正器上的有效覆盖范围,有利于后续AO系统对其波前畸变的校正补偿,释放变形镜的行程,减小了波前校正器对剩余波前畸变补偿校正的压力。本文利用矩阵光学光学传输矩阵理论进行光学整形扩束系统的初始结构参数的计算,并对初始结构进行优化。对优化后的光束整形系统做了仿真分析及验证实验。仿真及实验表明,本课题设计的光束整形系统可以将1.5mm×15mm的矩形光束整形扩束为尺寸在15mm×15mm至20mm×20mm范围内变化的方形准直光束,并且能够较好地达到光束整形与像差补偿的效果。板条激光器出射的光束经过整形系统后,其光束波前像差有较大的改善,远场能量集中度大大增加。
[Abstract]:In recent years, through continuous research, slab lasers are developing step by step on the road of high power and high beam quality. However, the geometric symmetry structure of slab laser and the design of Zigzag optical path are expected to solve the thermal effects such as thermal depolarization and thermal focusing of solid-state lasers in theory, but the experimental results are far from the theoretical expectation. The multi-mode output, misalignment, dynamic distortion and uneven pump gain result in the output power and beam quality of the slab laser are not up to the theoretical calculation results. In addition. The slab laser outputs a rectangular beam with a large aspect ratio, and its non-axisymmetric intensity distribution limits the application of this kind of laser. The output beam has defocus and astigmatic wavefront distortion, and its long and narrow beam divergence angles are different, resulting in the dispersion of focusing spot and the decrease of far-field energy concentration, which leads to the decline of beam quality. In order to solve the above problems, an optical beam shaping and expanding system for slab laser is designed, and its simulation analysis and experimental verification are done. Considering that the output beam of slab laser is a rectangular beam, the energy distribution in the long and narrow direction of the output beam is analyzed, and the energy distribution of the beam in the narrow direction is similar to that of Gao Si. The energy distribution of the long beam is ultra high and flat top, so the output beam of the slab laser is simulated in Zemax, which lays a foundation for the subsequent optimization of the shaping and expanding system. The advantages and disadvantages of several typical beam shaping methods are compared and analyzed, and the idea of designing beam shaping and expanding system using cylindrical lens and spherical lens as components is put forward. The shaping and expanding system designed in this paper has a certain dynamic range for the width and divergence angle of the incident beam. It is a semi-automatic optical shaping system between the passive shaping compensation system designed for a single parameter and the active optical shaping system. For experiments that require further beam purification with adaptive optical systems, the rectangular beam emitted by the slab laser is a square beam after the beam shaping and expanding system designed in this paper. The effective coverage of the beam on the wavefront corrector is increased, which is beneficial to the compensation of the wavefront distortion in the follow-up AO system, the release of the travel of the deformable mirror, and the reduction of the pressure of the wavefront corrector to compensate the residual wavefront distortion. In this paper, the initial structure parameters of optical shaping and beam expanding system are calculated by using matrix optical transfer matrix theory, and the initial structure is optimized. The optimized beam shaping system is simulated and verified. The simulation and experiments show that the beam shaping system designed in this paper can transform the rectangular beam of 1.5mm 脳 15mm into a square collimated beam whose size varies from 15mm 脳 15mm to 20mm 脳 20mm, and can better achieve the effect of beam shaping and aberration compensation. After the beam from slab laser passes through the shaping system, the wavefront aberration of the beam is greatly improved, and the far-field energy concentration is greatly increased.
【学位授予单位】：中国科学院研究生院（光电技术研究所）
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248.1

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