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基于激光加载的材料状态方程的实验研究对靶面光强分布的均匀性及稳定性提出了极高的要求, 靶面光强的上述两大特性在很大程度上决定了实验结果的精度和可重复性. 本文针对传统窄带高相干激光装置在激光加载材料状态方程实验中表现出的靶面光强均匀性和光强分布稳定性两方面可能存在的问题, 提出了基于宽带低相干激光, 利用消衍射阵列透镜联合诱导非相干技术的束匀滑方案, 并重点分析了波前相位畸变对靶面不均匀性及稳定性的影响. 模拟结果表明, 该方法明显降低了靶面不均匀性, 提高了对波前相位畸变的包容度, 获得了均匀、稳定的光强分布. 统计分析显示, 焦斑强度分布极差和不均匀性与波前相位畸变均方根梯度相关性较强. 因此, 可以根据统计结果以及实验对焦斑强度分布的要求, 给出波前相位畸变的容差范围, 对状态方程实验中激光驱动器参数的设计与优化具有指导意义.The experimental study of laser-driven material state equation puts forward extremely high requirements for the uniformity and stability of the target spot intensity distribution, and these two characteristics greatly determine the accuracy and repeatability of the experimental results. In this paper, a beam smoothing scheme combining diffraction-weakened lens array (LA) with induced spatial incoherent (ISI) technique based on low-coherence laser is proposed to solve the problems, that is, the uniformity and stability of the target spot intensity distribution in the material state equation experiments driven with narrow-band coherent laser. The super-Gaussian soft aperture used in our scheme can improve the intensity fluctuation caused by the hard-edge diffraction of the lens elements, and the temporal smoothing technique, ISI, can reduce the interference effect between the lens array elements. The speckle patterns of target spot, which are caused by interference between beamlets and determine the high nonuniformity, will randomly reconstruct after each coherent time. The high-frequency components are further smoothed by the time-average effect. In broadband high-power laser devices, ISI can be combined with LA by making the lens elements with different thickness values. This scheme can enhance the focal spot uniformity and improve the tolerance of the system to the wavefront phase distortion. The influence of wavefront phase distortion on target surface uniformity and stability are analyzed. The simulation results show that this smoothing scheme significantly reduces the target spot nonuniformity, improves the tolerance of random wavefront phase distortion, and presents a uniform and stable target spot intensity distribution. The nonuniformity of target spot will be reduced to about 10% after 10 ps, and about 3% after 100 ps. In addition, statistical analysis shows that the peak-to-valley value and the nonuniformity of the target spot intensity distribution are strongly correlated with the gradient of root-mean-square of the wavefront phase distortion. Using this method, the tolerance range of the wavefront phase distortion can be given according to the requirements of the experiments, which has reference value for designing and optimizing the laser driver parameters in the state equation experiment.
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Keywords:
- beam smoothing /
- high-power laser driver /
- lens array /
- introduced
[1] Lin Y, Kessler T, Lawrence G 1996 Opt. Lett. 21 1703Google Scholar
[2] Kato Y, Mima K, Miyanaga N, Arinaga S, Kitagawa Y, Nakatsuka M, Yamanaka C 1984 Phys. Rev. Lett. 53 1057Google Scholar
[3] Deng X M, Liang X C, Chen Z Z, Yu W Y, Ma R Y 1986 Appl. Opt. 25 3377
[4] 江秀娟, 李菁辉, 朱俭, 林尊琪 2015 物理学报 64 054201Google Scholar
Jiang X J, Li J H, Zhu J, Lin Z Q 2015 Acta Phys. Sin. 64 054201Google Scholar
[5] 周冰洁, 钟哲强, 张彬 2012 物理学报 61 214002
Zhou B J, Zhong Z Q, Zhang B 2012 Acta Phys. Sin. 61 214002
[6] Skupsky S, Short R, Kessler T, Craxton R, Letzring S, Soures J 1989 J. Appl. Phys. 66 3456Google Scholar
[7] Skupsky S, Craxton R, Skupsky S, Craxton R S 1999 Phys. Plasmas 6 2157Google Scholar
[8] Miyaji G, Miyanaga N, Urushihara S, Suzuki K, Matsuoka S, Nakatsuka M 2002 Opt. Lett. 27 725Google Scholar
[9] Obenschain S, Grun J, Herbst M, Kearney K, Manka C, McLean E, Mostovych A, Stamper A, Whitlock R, Bodner S, Gardner J, Lehmberg R 1986 Phys. Rev. Lett. 56 2807Google Scholar
[10] Obenschain S, BodnerS, Colombant D, Gerber K, Lehmberg R, McLean E, Mostovych A, Pronko M, Pawley C, Schmitt A, Sethian J, Serlin V, Stamper J, Sullivan C 1996 Phys. Plasmas 3 5
[11] Rothenberg J 2000 J. Appl. Phys. 87 3654Google Scholar
[12] Wang Y C, Wang F, Zhang Y, Huang X X, Hu D X, Zheng W G, Zhu R H, Deng X W 2017 Appl. Opt. 56 8087Google Scholar
[13] Zhong Z Q, Hou P C, Zhang B 2015 Opt. Lett. 40 5850Google Scholar
[14] Weng X F, Li T F, Zhong Z Q, Zhang B 2017 Appl. Opt. 56 8902Google Scholar
[15] Haynam C, Wegner P, Auerbach J, Bowers M, Dixit S, Erbert G, Heestand G, Henesian M, Hermann M, Jancaitis K, Manes K, Marshall C, Mehta N, Menapace J, Moses E, Murray J, Nostrand M, Orth C, Patterson R, Sacks R, Shaw M, Spaeth M, Sutton S, Williams W, Widmayer C, White R, Yang S, Wonterghem B 2007 Appl. Opt. 46 3276Google Scholar
[16] Jiang X J, Li J H, Li H G, Li Y, Lin Z Q 2011 Appl. Opt. 50 5213Google Scholar
[17] 江秀娟, 李菁辉, 李华刚, 周申蕾, 李扬, 林尊琪 2012 物理学报 61 124202Google Scholar
Jiang X J, Li J H, Li H G, Zhou S L, Li Y, Lin Z Q 2012 Acta Phys. Sin. 61 124202Google Scholar
[18] Zhou S L, Lin Z Q, Jiang X J 2007 Opt. Commun. 272 186Google Scholar
[19] 陈泽尊, 向春, 邓锡铭 1985 中国激光 13 65Google Scholar
Chen Z Z, Xiang C, Deng X M 1985 Chin. J. Las. 13 65Google Scholar
[20] Regan S, Marozas J, Kelly J, Boehly T, Donaldson W, Jaanimagi P, Keck R, Kessler T, Meyerhofer D, Seka W 2000 J. Opt. Soc. Am. B 17 1483Google Scholar
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图 4 波前畸变造成的焦斑分布不均匀性及差异性 上排为波前相位理想分布及波前畸变, 下排为对应的焦斑强度分布
Fig. 4. The nonuniformity and difference of the focal spot distributions caused by wavefront distortion. The upper row is the ideal distribution of the wavefront phase and the wavefront distortion, and the lower row is the focal spot intensity distribution, respectively.
表 1 不同波前相位畸变, 焦斑不均匀度随匀滑时间的变化
Table 1. The nonuniformity of target at different smoothing time with different wavefront distortion.
T($\tau $) 1 10 100 1000 Inf $ \sigma ({\phi _0})$ 0.9716 0.3423 0.0956 0.0303 0.0060 $ \sigma ({\phi _1})$ 1.0267 0.3209 0.1012 0.0332 0.0118 $ \sigma ({\phi _2})$ 0.9374 0.3042 0.0989 0.0345 0.0158 -
[1] Lin Y, Kessler T, Lawrence G 1996 Opt. Lett. 21 1703Google Scholar
[2] Kato Y, Mima K, Miyanaga N, Arinaga S, Kitagawa Y, Nakatsuka M, Yamanaka C 1984 Phys. Rev. Lett. 53 1057Google Scholar
[3] Deng X M, Liang X C, Chen Z Z, Yu W Y, Ma R Y 1986 Appl. Opt. 25 3377
[4] 江秀娟, 李菁辉, 朱俭, 林尊琪 2015 物理学报 64 054201Google Scholar
Jiang X J, Li J H, Zhu J, Lin Z Q 2015 Acta Phys. Sin. 64 054201Google Scholar
[5] 周冰洁, 钟哲强, 张彬 2012 物理学报 61 214002
Zhou B J, Zhong Z Q, Zhang B 2012 Acta Phys. Sin. 61 214002
[6] Skupsky S, Short R, Kessler T, Craxton R, Letzring S, Soures J 1989 J. Appl. Phys. 66 3456Google Scholar
[7] Skupsky S, Craxton R, Skupsky S, Craxton R S 1999 Phys. Plasmas 6 2157Google Scholar
[8] Miyaji G, Miyanaga N, Urushihara S, Suzuki K, Matsuoka S, Nakatsuka M 2002 Opt. Lett. 27 725Google Scholar
[9] Obenschain S, Grun J, Herbst M, Kearney K, Manka C, McLean E, Mostovych A, Stamper A, Whitlock R, Bodner S, Gardner J, Lehmberg R 1986 Phys. Rev. Lett. 56 2807Google Scholar
[10] Obenschain S, BodnerS, Colombant D, Gerber K, Lehmberg R, McLean E, Mostovych A, Pronko M, Pawley C, Schmitt A, Sethian J, Serlin V, Stamper J, Sullivan C 1996 Phys. Plasmas 3 5
[11] Rothenberg J 2000 J. Appl. Phys. 87 3654Google Scholar
[12] Wang Y C, Wang F, Zhang Y, Huang X X, Hu D X, Zheng W G, Zhu R H, Deng X W 2017 Appl. Opt. 56 8087Google Scholar
[13] Zhong Z Q, Hou P C, Zhang B 2015 Opt. Lett. 40 5850Google Scholar
[14] Weng X F, Li T F, Zhong Z Q, Zhang B 2017 Appl. Opt. 56 8902Google Scholar
[15] Haynam C, Wegner P, Auerbach J, Bowers M, Dixit S, Erbert G, Heestand G, Henesian M, Hermann M, Jancaitis K, Manes K, Marshall C, Mehta N, Menapace J, Moses E, Murray J, Nostrand M, Orth C, Patterson R, Sacks R, Shaw M, Spaeth M, Sutton S, Williams W, Widmayer C, White R, Yang S, Wonterghem B 2007 Appl. Opt. 46 3276Google Scholar
[16] Jiang X J, Li J H, Li H G, Li Y, Lin Z Q 2011 Appl. Opt. 50 5213Google Scholar
[17] 江秀娟, 李菁辉, 李华刚, 周申蕾, 李扬, 林尊琪 2012 物理学报 61 124202Google Scholar
Jiang X J, Li J H, Li H G, Zhou S L, Li Y, Lin Z Q 2012 Acta Phys. Sin. 61 124202Google Scholar
[18] Zhou S L, Lin Z Q, Jiang X J 2007 Opt. Commun. 272 186Google Scholar
[19] 陈泽尊, 向春, 邓锡铭 1985 中国激光 13 65Google Scholar
Chen Z Z, Xiang C, Deng X M 1985 Chin. J. Las. 13 65Google Scholar
[20] Regan S, Marozas J, Kelly J, Boehly T, Donaldson W, Jaanimagi P, Keck R, Kessler T, Meyerhofer D, Seka W 2000 J. Opt. Soc. Am. B 17 1483Google Scholar
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