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题名	MOPA激光系统波前检测技术
作者	邓泽微
学位类别	硕士
答辩日期	2008
授予单位	中国科学院上海光学精密机械研究所
导师	施翔春
关键词	波前检测 环路径向剪切干涉 波前重建 MOPA激光系统
其他题名	MOPA Laser System Wavefront Sensing Technology
中文摘要	主振荡功率放大器（MOPA）激光系统的关键问题，在于放大器光泵浦过程中的热效应使光束波前产生畸变。其研究方向和内容集中在提高输出功率，改善光束质量。对波前畸变的原因进行分析、对波前畸变的情况进行检测，就能够采用自适应光学方法进行波前校正或者对激光器结构进行相应的改进，从而提高激光器的输出光束质量。本课题主要研究了采用环路径向剪切干涉仪来对MOPA激光系统中产生的波前畸变进行检测的相关技术。 本文调研了国内外波前检测技术的现状，对一些常见的波前检测方法进行了比较。相对于其它波前检测方法（如哈特曼传感器，曲率传感器，横向剪切干涉仪），环路径向剪切干涉具有以下优点：不需要设置专门的参考光，光路较为简单；物光与参考光共光路，对环境的振动和温度、气流的变化能产生彼此共模抑制，一般无需隔振动和恒温条件也能获得稳定的干涉条纹；可通过调节剪切比来改变测量精度。 本文论述了环路径向剪切干涉仪的工作原理，并给出了系统的波前重建算法、波面拟合算法、波前曲率半径拟合算法、以及等效透镜焦距反推算法。然后以一个之字形板条增益介质为例，对环路径向剪切干涉仪进行了系统仿真。此外，还对文献中给出的一幅实测的干涉条纹图进行波前重建和波面拟合，得到了和原文相同的结果，这证明了上述算法的正确性。 最后，在上述理论计算的指导下，进行了一系列波前检测实验： 对一个焦距已知的平凹透镜所产生的波前畸变进行了检测，总的测量的误差小于8%，验证了系统测量结果的准确性； 测量了一个单侧泵浦的之字形板条增益介质，在不同泵浦功率下的波前畸变情况。在沿垂直于之字形光路所在平面的方向上，波前近似为汇聚的球面波；在另一方向上则近似为倾斜的平面波。 测量了一个双侧面泵浦的板条增益介质，在不同泵浦功率下的波前畸变情况。在沿泵浦光的方向上，波前近似为汇聚的球面波；在另一方向上则表现为倾斜的平面波。最后还测量了在泵浦源打开瞬间，增益介质的热透镜焦距随时间的变化情况，其达到热稳所需的时间大约为几秒钟。
英文摘要	The critical problem of master oscillator power amplifier (MOPA) system is the wavefront distortion of optical amplifier, resulting from the thermal effects of optical pumping. Related researches concentrated on raising the output laser power, and improving the light beam quality. If we can analyze the causes of the wavefront distortion and measure the wavefront, the measured data can be used to guide the correction of the wavefront or the improvement of the laser structure. So the output beam quality can be improved. This article mainly concerned on the wavefront sensing technology of MOPA laser system, using a CRWSI. The background of wavefront sensing technology was investigated. Some common methods of wavefront sensing were compared. Comparing to other methods, such as Hartman sensor, curvature sensor, and lateral wavefront shearing interferometer, the merit of CRWSI was as follows: First, extra reference light was not necessary, so the light path was not complicate. Second, the reference light and the signal light were in common path, so it can generate common-mode rejection against vibration, variation of the flow, and temperature variation. Thus stable interference pattern can be obtained without vibration isolation and thermal insulation. Third, the measurement accuracy can be adjusted by the shearing ratio. The principle of CRWSI was presented. Then some related algorithms were explained, including the wavefront reconstruction algorithm, the wavefront fitting algorithm, the radius of wavefront curvature fitting algorithm, and the focus length of equivalent lens deducing algorithm. Taking the zigzag slab gain medium for example, the CRWSI system was simulated. Furthermore, an actual interference pattern from another paper was reconstructed and fitted. The result was the same as it was in that paper. This proved the algorithm mentioned above. At last, guided by the theoretical calculation mentioned above, a series of experiments were carried out. The wavefront distortion of a plano concave lens was measured. The total error was less then 8%. This certified the measured results of the interferometer. The wavefront distortion of a one-side pumped zigzag slab gain medium in different pumping power was measured. Along the direction vertical to the zigzag plan, the wavefront was similar to converging sphere wave. In the other direction, the wavefront was similar to tilted plan wave. The wavefront of a bilateral pumped slab gain medium in different pumping power was measured. Along the pumping light direction, the wavefront was similar to converging sphere wave. In the other direction, the wavefront was similar to tilted plan wave. The wavefront distortion variation with time was also measured, when the pumping source was turned on. It took a few second to reach steady state.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16385]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	邓泽微. MOPA激光系统波前检测技术[D]. 中国科学院上海光学精密机械研究所. 2008.

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