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题名:
基于自适应光学的光束相干合成研究
作者: 杨若夫
学位类别: 博士
答辩日期: 2009-05-31
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 姜文汉
关键词: 相干合成 ; 自适应光学 ; 平移位相探测 ; 能动分块反射镜 ; 条纹提取算法
其他题名: The investigation of coherent combining based on adaptive optics
学位专业: 光学工程
中文摘要: 自世界第一台激光器诞生伊始研制高功率以及良好光束质量的激光器就成为了国内外研究的重点。但是,在提高激光器的输出功率的同时,带来的一个非常大的问题是光束质量急剧下降。 而利用相干合成技术则为这一矛盾问题的解决带来转机。它要求每一路是相干光束,也就是要满足四个条件即方向、频率、偏振以及相位要保持一致。采用此技术可以将多路光束质量好但功率较弱的激光光束合成一路功率高并且光束质量好的光束。在四个条件中,前三个比较容易解决,而相位的控制则是在相干合成技术里面最具有挑战性的一个问题。对多路相干激光光束的相位保持一致要求相位探测器能足够快的探测到相位变化并反馈给校正器从而足够快的对光束相位进行实时校正。 自适应光学是对一束有像差的波前进行实时补偿的技术。对于单路光束,自适应光学主要是校正光束的倾斜、球差、彗差、象散等高阶像差而对光束的平移位相则不做校正。而在相干合成技术中,由于单路光束的光束质量比较好,平移位相的校正则成为了影响远场合成光斑质量的最为重要的一个因素。 本文将自适应光学技术应用于相干合成领域,研究了如何利用自适应光学对光束之间的平移位相进行实时补偿,并围绕光束的平移位相差对远场合成图样的影响进行了深入分析。在自适应光学应用于相干合成技术中,波前校正器是分块的能动反射镜,它不同于传统的自适应光学上所采用的变形反射镜,每一个分块反射镜对每一路光束进行平移位相以及光束的倾斜进行补偿而对其余的高阶则不做校正。 本文首次提出了探测平移位相的“条纹提取算法”。通过理论分析以及公式推导、仿真计算验证了“条纹提取算法”的可行性。此算法可以直接测量得到两路相干光束的平移扰动幅度与时间的关系,而在传统的相位探测中,采用光电二极管只能得到光强信息变化,由于平移位相具有半波长模糊性,因此光强信息的变化并不能直接代表平移相位幅度的变化。本文将此算法应用于不同功率下的两路光纤放大器的位相探测中,得到了良好的试验结果。 对于平移位相差的校正,本文从原理出发,提出了多个校正方案。从原理实验上得到了两路的位相校正的可行性以及采用自适应光学方案对动态平移相位扰动的校正能力,并完成了毫瓦量级的两路光纤放大器以及10瓦级的两路光纤放大器的实时校正。最后,本文研究了三路情况下的自适应相干合成的可行性并完成了三路相干合成的验证试验。 总而言之,本文利用自适应光学技术作为基础,研究了此技术应用于光束相干合成领域的可行性。基于此技术,首次完成了在不同功率下的两路光纤放大器的相干合成实验,同时提出了相干光束探测平移位相的一种新的方法。对以后将自适应光学技术应用于更高功率、更多路数下的相干合成积累了一定程度的理论和工程经验。
英文摘要: Since the birth of the world's first laser, the development of high power and good beam quality lasers have become the focus of the study at home and abroad. However, a critical issue is brought about is that the beam quality has dropped drastically while increasing the output power of laser. Coherent combining technology used for this contradictory problem turn for the better. It requires each beam is coherent, that is, to satisfy the four conditions: direction, frequency, polarization and phase in order to maintain consistency. The application of this technology can combine each beam with good quality but low power to only one beam with good quality as well as higher power. In the four conditions, the first three is relatively easy to solve, whereas, the phase control issue is the most challenging problem in coherent combining technology. In multi-beam coherent combining, keeping the phases of laser beams unanimous requests the phase detector can be quick enough to detect changes of phase noise and phase corrector can be quick enough to compensate the phase noise obtained by phase detector. Adaptive optics technology is used to compensate the wave-front aberrations of single beam in real time. As for single beam, adaptive optics corrects these aberrations such as tilt, spherical aberration, coma, etc rather than piston aberration. However, in the coherent combining technology, because quality of each beam is better, the correction to piston aberration becomes the most important issue which impacts the combining pattern quality in far-field. In this paper, adaptive optics technology will be applied to the field of coherent combining and we study how to make use of adaptive optics on the phase correcting between coherent beams. We also deeply analyze the effect about how the piston aberration impacts the far-field combining pattern. In adaptive optics technology applied to coherent combining system, the wave-front corrector is active segmented mirror which is different from the deformable mirror applied in traditional adaptive optics. Active segmented mirror in coherent combining compensates piston and tilt aberrations of each beam. As for high-order aberration, active segmented mirror hasn’t the ability to correct these aberrations. This article first proposed the "Fringe Extraction Algorithm" to detect the piston aberration between coherent beams. We verify the feasibility of Fringe Extraction Algorithm through theoretical analysis, formula derivation and simulation. This algorithm can be applied to directly measure the relation between piston amplitude and time in two coherent beams. But, the traditional phase detection theme employs photodiode which can only obtain information about light intensity. Because of half- wavelength ambiguity, light intensity information should not directly represent the phase amplitude changes. In this paper, this algorithm is applied to measure the phase noise of two fiber amplifiers under different power lever and good experimental results are presented. About the correction to piston aberration, this article puts forward several calibration programs based on fundamental principle. From the principle experiment, the feasibility of calibration to piston aberration is presented and the correcting ability to dynamic piston aberration is concluded. Besides, two m-W and 10-W fiber amplifiers are phase-locked in real time by adaptive optics configuration. Finally, this paper studies the feasibility of three-beam coherent combining based on adaptive optics and performs the test experiment. In short, this paper studies the feasibility in coherent combining configuration based on adaptive optics. Based on this technology, coherent combining experiments with two fiber amplifiers are performed in the first time. Meanwhile, a novel method to measure the piston aberration between two beams is presented. And, it accumulates some theoretical and engineering experience in the coherent combining configuration with higher power and more elements based on adaptive optics.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/340
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
杨若夫. 基于自适应光学的光束相干合成研究[D]. 光电技术研究所. 中国科学院光电技术研究所. 2009.
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