基于复合型光栅组合的多色集束匀滑方案
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摘要
提出了基于复合型光栅组合的多色集束匀滑方案,可实现激光集束在靶面上平移和旋转两种运动方式的组合。建立了靶面散斑的横向扫动速度物理模型,并推导出激光束横向扫动速度的解析表达式,进而讨论了靶面横向扫动速度的变化规律。在此基础上,分析了不同复合型光栅组合对靶面辐照均匀性的影响,并对复合型光栅参数的选取进行了优化。结果表明,与传统的线性光栅色散匀滑方案相比,在使用复合型光栅时激光束靶面散斑的扫动速度和扫动方向更加复杂,因而其匀滑效果更佳。与典型的束匀滑方案进行对比,经过优化的基于复合型光栅组合的多色集束匀滑方案能够有效改善焦斑均匀性和抑制焦斑内部热斑比例。此外,采用功率谱密度曲线对激光束纵向强度分布特性进行初步分析,结果发现,基于复合型光栅组合的多色集束匀滑方案能有效降低激光束纵截面峰值强度。
A beam smoothing scheme for multi-color laser quad based on combination of hybrid gratings is proposed,which can achieve a combination of transverse and rotary moving of the speckles on target plane.The physical model of the transverse moving speed of the speckles on target plane is built up,and the analytical expression for the transverse moving speed of the speckles on target plane is also derived.Furthermore,the variation of the transverse moving speed of the speckles on target plane is discussed.On the basis,the influences of different combinations of hybrid gratings on irradiation uniformity on target plane are analyzed,and the parameters of hybrid gratings are optimized.Results indicate that,compared with the traditional scheme of smoothing by spectral dispersion based on linear gratings,the moving speed and direction of the speckles on target plane are more complicated based on hybrid gratings,resulting in the further improvement of the smoothing effect.Compared to the typical schemes of beam smoothing,the optimized scheme of beam smoothing for multi-color laser quad based on the combination of hybrid gratings can effectively improve the irradiation uniformity and reduce the ratio of hot spots.Additionally,the power spectral density is proposed and used to preliminarily analyze the longitudinal intensity distribution characteristics of laser quad,and it is found that the beam smoothing for multi-color laser quad based on the combination of hybrid gratings can effectively decrease longitudinal peak intensity of laser quad.
A beam smoothing scheme for multi-color laser quad based on combination of hybrid gratings is proposed,which can achieve a combination of transverse and rotary moving of the speckles on target plane.The physical model of the transverse moving speed of the speckles on target plane is built up,and the analytical expression for the transverse moving speed of the speckles on target plane is also derived.Furthermore,the variation of the transverse moving speed of the speckles on target plane is discussed.On the basis,the influences of different combinations of hybrid gratings on irradiation uniformity on target plane are analyzed,and the parameters of hybrid gratings are optimized.Results indicate that,compared with the traditional scheme of smoothing by spectral dispersion based on linear gratings,the moving speed and direction of the speckles on target plane are more complicated based on hybrid gratings,resulting in the further improvement of the smoothing effect.Compared to the typical schemes of beam smoothing,the optimized scheme of beam smoothing for multi-color laser quad based on the combination of hybrid gratings can effectively improve the irradiation uniformity and reduce the ratio of hot spots.Additionally,the power spectral density is proposed and used to preliminarily analyze the longitudinal intensity distribution characteristics of laser quad,and it is found that the beam smoothing for multi-color laser quad based on the combination of hybrid gratings can effectively decrease longitudinal peak intensity of laser quad.
引文
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[19]Rothenberg J E.Implementation of smoothing by spectral dispersion on Beamlet and NIF[J].Proceedings of SPIE,1999,3492:970-979.
[20]Zhou B J,Zhong Z Q,Zhang B.Influence of beam moving characteristics on smoothing effect of focal spot[J].Acta Physica Sinica,2012,61(21):214202.周冰洁,钟哲强,张彬.光束运动特性对焦斑束匀滑效果的影响[J].物理学报,2012,61(21):214202.
[21]Zhong Z Q,Hou P C,Zhang B.A novel radial beam smoothing scheme based on optical Kerr effect[J].Acta Physica Sinica,2016,65(9):094207.钟哲强,侯鹏程,张彬.基于光克尔效应的径向光束匀滑新方案[J].物理学报,2016,65(9):094207.
[22]Divol L,Berger R L,Meezan N B,et al.Threedimensional modeling of laser-plasma interaction:benchmarking our predictive modeling tools versus experiments[J].Physics of Plasmas,2008,15(5):085001.
[23]Peng Z T,Jing F,Liu L Q,et al.Power spectra density estimation of quality of the laser beam passing through an self-focusing media[J].Acta Physica Sinica,2005,52(1):87-90.彭志涛,景峰,刘兰琴,等.自聚焦激光束光束质量评价的功率谱密度方法[J].物理学报,2005,52(1):87-90.
[2]Schiavi A,Atzeni S,Marocchino A.Illumination stability for high-repetition-rate laser facilities in directdrive inertial confinement fusion[J].Europhysics Letters,2011,94(3):35002.
[3]Lindl J.Development of the indirect-drive approach to inertial confinement fusion and the target physics basis for ignition and gain[J].Physics of Plasmas,1995,2(11):3933-4024.
[4]Wen P,Li Z L,Zhong Z Q,et al.Study on propagation characteristics of laser quads in cylindrical hohlraum for indirect drive facility[J].Acta Optica Sinica,2017,36(1):0114001.文萍,李泽龙,钟哲强,等.间接驱动装置中柱形腔内激光束传输叠加特性研究[J].光学学报,2017,36(1):0114001.
[5]Lindl J D,Amendt P,Berger R L,et al.The physics basis for ignition using indirect-drive targets on the National Ignition Facility[J].Physics of Plasmas,2004,11(2):339-491.
[6]Kato Y,Mima K,Miyanaga N,et al.Random phasing of high-power lasers for uniform target acceleration and plasma-instability suppression[J].Physical Review Letters,1984,53(11):1057-1060.
[7]Dixit S N,Lawson J K,Manes K R,et al.Kinoform phase plates for focal plane irradiance profile control[J].Optics Letters,1994,19(6):417-419.
[8]Néauport J,Ribeyre X,Daurios J,et al.Design and optical characterization of a large continuous phase plate for laser integration line and laser megajoule facilities[J].Applied Optics,2003,42(13):2377-2382.
[9]Skupsky S,Short R W,Kessler T,et al.Improved laser-beam uniformity using the angular dispersion of frequency-modulated light[J].Journal of Applied Physics,1989,66(8):3456-3462.
[10]Hou P,Zhong Z Q,Zhang B.Analysis and optimization of radial smoothing based on optical Kerr effect for irradiation improvement[J].Optics&Laser Technology,2016,85:48-54.
[11]Zheng T R,Zhang Y,Geng Y C,et al.Smoothing by spectral dispersion technology based on bundle multiple-frequency modulation[J].Chinese Journal of Lasers,2017,44(12):1205003.郑天然,张颖,耿远超,等.基于集束多频调制的光谱色散匀滑技术[J].中国激光,2017,44(12):1205003.
[12]Haynam C A,Wegner P J,Auerbach J M,et al.National Ignition Facility laser performance status[J].Applied Optics,2007,46(16):3276-3303.
[13]Temporal M,Canaud B,Garbett W J,et al.Numerical analysis of the direct drive illumination uniformity for the Laser Mega Joule facility[J].Physics of Plasmas,2014,21(1):012710.
[14]Zhang R,Jia H,Tian X,et al.Research of beam conditioning technologies using continuous phase plate,multi-FM smoothing by spectral dispersion and polarization smoothing[J].Optics&Lasers in Engineering,2016,85:38-47.
[15]Zhong Z Q,Zhang B.Beam smoothing characteristics of multi-central frequency and multicolor smoothing by spectral dispersion[J].Applied Optics,2014,53(10):2020-2025.
[16]Zhang R,Zhang X,Sui Z,et al.Research on target uniform irradiation method using linearly modulated light and special grating dispersion[J].Optics&Laser Technology,2011,43(7):1073-1077.
[17]Wang J,Hou P C,Zhang B.A new scheme of spectral dispersion smoothing based on hybrid grating[J].Acta Physica Sinica,2016,65(20):204201.王健,侯鹏程,张彬.基于复合型光栅的光谱色散匀滑新方案[J].物理学报,2016,65(20):204201.
[18]Wen P,Li Z L,Zhong Z Q,et al.Parameters optimization for multi-color multi-central frequency smoothing by spectral dispersion[J].Acta Optica Sinica,2015,35(6):0614001.文萍,李泽龙,钟哲强,等.多色、多频光谱角色散匀滑技术的参数优化[J].光学学报,2015,35(6):0614001.
[19]Rothenberg J E.Implementation of smoothing by spectral dispersion on Beamlet and NIF[J].Proceedings of SPIE,1999,3492:970-979.
[20]Zhou B J,Zhong Z Q,Zhang B.Influence of beam moving characteristics on smoothing effect of focal spot[J].Acta Physica Sinica,2012,61(21):214202.周冰洁,钟哲强,张彬.光束运动特性对焦斑束匀滑效果的影响[J].物理学报,2012,61(21):214202.
[21]Zhong Z Q,Hou P C,Zhang B.A novel radial beam smoothing scheme based on optical Kerr effect[J].Acta Physica Sinica,2016,65(9):094207.钟哲强,侯鹏程,张彬.基于光克尔效应的径向光束匀滑新方案[J].物理学报,2016,65(9):094207.
[22]Divol L,Berger R L,Meezan N B,et al.Threedimensional modeling of laser-plasma interaction:benchmarking our predictive modeling tools versus experiments[J].Physics of Plasmas,2008,15(5):085001.
[23]Peng Z T,Jing F,Liu L Q,et al.Power spectra density estimation of quality of the laser beam passing through an self-focusing media[J].Acta Physica Sinica,2005,52(1):87-90.彭志涛,景峰,刘兰琴,等.自聚焦激光束光束质量评价的功率谱密度方法[J].物理学报,2005,52(1):87-90.