共查询到20条相似文献,搜索用时 94 毫秒
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用光强沿x轴方向呈线性变化的方形环状光束模拟高功率激光,利用自编四维仿真程序对高功率激光在光束控制系统中的传输作了详细的数值计算研究。结果表明:热效应使远场光束的峰值光强和可聚焦能力下降。入射光强的非均匀分布进一步降低峰值光强和可聚焦能力,导致远场光束重心和峰值光强位置移动,并产生像散。光束的非均匀程度越高,远场光束质量越差。横向风和轴向风对热效应均有抑制作用。然而,轴向风不会引起远场光束重心偏移和像散,但是轴向风比横向风建立稳态所用时间更长。 相似文献
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对激光惯性约束聚变(ICF)驱动器终端光学系统中连续相位板(CPP)的位置优化进行了研究.根据高强度激光非线性及微扰传输理论计算了CPP前置时激光通过频率转换系统以后的近远场光束特性和系统的三倍频转换效率.研究发现,前置于基频光路的CPP对三倍频转换效率和出射光束特性均有影响,但只要远场圆形焦斑直径小于05 mm,三倍频转换效率的下降与出射光束通量对比度的上升均在容许范围之内,同时远场焦斑形态和能量集中度也符合设计要求.对于实现远场小焦斑匀滑的CPP前置于ICF的基频光路中进行光束匀滑和整形,不会对IC
关键词:
连续相位板
束匀滑元件
惯性约束聚变
光束通量对比度 相似文献
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为了解决高功率激光装置光束质量诊断系统的自验证问题,研究了基于空间相位调制的径向剪切干涉法综合诊断光束质量的实验应用。该方法理论上只需一台干涉仪且从单幅干涉图中获取光束的近场、相位和远场分布信息。实验结果表明,目前可以得到高分辨率的相位分布,由测量近场和相位恢复出的远场同CCD直接测量得到的远场形态相同,环围能量比曲线相当吻合,不足之处在于只能提取近场较低空间频率成分,还达不到CCD直接测量的空间分辨水平。 相似文献
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Guoquan Zhou 《Optics & Laser Technology》2012,44(1):218-225
Based on the vector angular spectrum method and the method of stationary phase, an analytical expression for the vectorial structure of the far field of an elegant Hermite–Gaussian beam is derived. The analytical formulae of the energy flux distributions of the TE term, the TM term, and the whole beam are presented in the far field. Analytical expressions for the ratios of the powers of the TE and TM terms to those of the elegant Hermite–Gaussian beam are obtained without any approximation. The physical pictures of the far field of an elegant Hermite–Gaussian beam are demonstrated and compared with those of the far field of the corresponding standard Hermite–Gaussian beam. This research reveals the internal vectorial structure of the far field of an elegant Hermite–Gaussian beam from an alternative viewpoint. 相似文献
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Far field structural characteristics of cosh-Gaussian beam 总被引:1,自引:0,他引:1
By means of the theorem of the vectorial structure of electromagnetic beams and the method of stationary phase, the analytical vectorial structure of cosh-Gaussian (ChG) beam in the far field is presented. The light intensity distributions of a ChG beam and its vectorial structure are investigated in the far field. In addition, the influence of the parameters associated with the cosh term on the light intensity distributions of the whole beam and its structure are also analyzed. The analytical formulae obtained here are applicable not only to the non-paraxial case, but also to the paraxial case. The physical picture of ChG beam in the far field is well depicted from the vectorial structure. 相似文献
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Free and forced motions of submerged one-dimensional waveguides have been investigated. Both the submerged beam and the submerged string can support a wave system which includes a pure surface wave in the fluid adjoining the waveguide, provided that certain conditions on the frequency (for the beam) or the physical parameters of the system (for the string) are satisfied. Dispersion curves are presented for steel beams and steel strings in water. Steady-state solutions have been derived for excitation by a concentrated time-harmonic load. The displacement responses at the point of application of the load and in the far field have been examined. Polar plots display and radiated far field in the fluid. At low frequencies the polar plots are circular in planes containing the waveguide, but the radiation pattern develops lobes as the frequency increases. Reflection, transmission and scattering into the fluid of an incident wave system by an elastic support of stiffness κ and mass m have also been examined, and the possibility of resonance phenomena has been investigated. 相似文献
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Propagation properties of off-axis Hermite--cosh--Gaussian beam combinations through a first-order optical system 下载免费PDF全文
Based on the Collins integral formula, the analytic expressions of propagation of
the coherent and the incoherent off-axis Hermite--cosh--Gaussian (HChG) beam
combinations with rectangular symmetry passing through a paraxial first-order
optical system are derived, and corresponding numerical examples are given and
analysed. The resulting beam quality is discussed in terms of power in the bucket
(PIB). The study suggests that the resulting beam cannot keep the initial intensity
shape during the propagation and the beam quality for coherent mode is not always
better than that for incoherent mode. Reviewing the numerical simulations of
Gaussian, Hermite--Gaussian (HG) and cosh--Gaussian (ChG) beam combinations
indicates that the Hermite polynomial exerts a chief influence on the irradiance
profile of composite beam and far field power concentration. 相似文献
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We propose and demonstrate the generation of dark hollow beam with plane wavefront in the near field based on a hybrid control
way by using dual phase only liquid crystal spatial light modulators (LC-SLMs). One phase only LC-SLM redistributes the intensity
to the target distribution based on refractive beam shaping system and the other phase only LC-SLM adaptively compensates
the wavefront of the output beam by using stochastic parallel gradient descent (SPGD) algorithm. Compared with conventional
refractive beam shaping system, the hybrid control way can not only improve the far-field energy concentration of the output
beam, but also can correct the phase distortion of the system. Influences of phase distortion on laser beam shaping are analyzed
in detail. The theoretical and experimental results show that the near-diffraction-limited dark hollow beam can be successfully
generated by using this hybrid control way. The power in the main lobe of the airy disk pattern area in the far field is 2.3
times larger than that without being adaptively compensated. 相似文献
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We propose a scanning imaging measurement method using two linear array charge coupled devices (CCD) to evaluate the transmission performance of the linear laser beam of 90° × 2°. The two linear array CCDs are placed at two positions in the far field separated by a definite angle. The beam divergence angles in the view direction are measured by linear fitting because the beam width conforms to the linear relationship in the far field. This method has the ability for real-time testing and is appropriate for the complicated beam shapes with a wide measurement range. 相似文献
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HONG Zhi CHEN Jun 《Chinese Journal of Lasers》2001,10(6):401-405
1 Introduction SemiconductorlaserarrayshavereachedhighoutputpowerofseveralWincontinuous waveoperation[1] ,butduetothepoorspatialcoherenceandbeam profile ,applicationsarelimited .Inordertoenhancethespatialcoherence,thenumberoftransversemodesmustbereduced ,w… 相似文献
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Abstract An external cavity for the laser diode array with a conventional mirror in what we call two-time self-injection operation is presented. The external cavity consists of two lenses, a flat external mirror(EM) in the image plane of the array and a prism that is used as an output coupler. The single-lobed near diffraction-limited far field beam of a 1 W 10-stripe gain-guided LD array lies at 6.4°~9° with the external cavity operation in two-time self-injection mode, whereas at 2.5°~3.0° for its normal feedback operation. The width of the far field beam (FWHM) is 0.43° and 0.63° at driving current of 2 and 3.2 ×Ithr, respectively, much narrower than that in normal feedback operation, but at the expense of lower output power. The output of the system is very stable and insensitive to the tilt and position of the EM. 相似文献
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为了提高980nm半导体激光器的输出功率并获得较小的远场发散角,在非对称波导结构的基础上设计了n型波导结构,即在n型波导中引入高折射率的内波导层。采用理论计算和SimLastip软件模拟对常规非对称波导结构和内波导结构进行了研究。利用分子束外延系统生长980nm内波导结构的外延材料,并制作了激光器。对于条宽为100μm、腔长为1000μm的器件,阈值电流为97mA,斜率效率为1.01W/A;当注入电流为500mA时,远场发散角为29°(垂直向)×8°(水平向),与模拟结果相符。理论计算和实验结果表明:较之于常规非对称波导结构,内波导结构可有效降低光场限制因子,提高输出功率,减小远场发散角。 相似文献
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采用Strehl比、桶中功率、β参数和束宽描述远场光束质量,研究了光束控制系统热效应和球差对远场激光光束质量的影响.用四维仿真程序作了详细计算,给出了数值计算结果并进行了物理分析.研究表明,传输通道的热效应和正球差会使远场光强分布扩展,可聚焦能力下降,光束质量变差.有意义的是,当激光发射功率达到一定值时,合适选取负球差会在几何焦面得到比无球差时更高的峰值光强和更好的可聚焦能力.但在以前的工作中,由于焦移,类似的结论是在实际焦面上得出的.非线性热晕的存在是其物理原因,对此用数值计算例子作了说明.
关键词:
高功率激光
热效应
光束控制系统
球差 相似文献
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The approximate analytical expressions of the apertured broadband beams in the far field with Gaussian and Laguerre-Gaussian spatial modes are presented.For the radially polarized Laguerre-Gaussian beam,the result reveals that the electromagnetic field in the far field is transverse magnetic.The influences of bandwidth(Γ) and truncation parameter(C 0) on the transverse intensity distribution of the Gaussian beam and on the energy flux distribution of radially polarized Laguerre-Gaussian beam are analysed. 相似文献
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基于广义惠更斯-菲涅耳原理,并采用光束的非相干合成方法,推导出了M×N双曲余弦高斯列阵光束在湍流中的三维光强传输方程.采用桶中功率、β参量和Strehl比作为光束质量的评价参量,研究了湍流大气对双曲余弦高斯列阵光束远场光束质量的影响.研究表明:在湍流大气中,双曲余弦高斯列阵光束的传输将经历三个阶段的变化,并且湍流使得光束传输经历三阶段的进程加快;湍流导致双曲余弦高斯列阵光束扩展、最大峰值光强下降,但是,β参量随光束数目M(N)、相邻子光束间距xd(yd)和光束参量δ的增加而减少,即光束扩展受湍流的影响减小;并且,存在最佳xd(yd)和δ值使得Strehl比取得极大值.因此,适当选取M(N)、xd(yd)和δ可以降低湍流对双曲余弦高斯列阵光束远场光束质量的影响. 相似文献