共查询到19条相似文献,搜索用时 138 毫秒
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建立了超高斯光束的相干叠加的数学模型,对比了光束间距为1 cm、超高斯阶数为12条件下25束高斯光束相干叠加与非相干叠加时的光强分布,发现相干合成的峰值光强为非相干叠加的峰值光强的近10倍,且光束质量也得到大大提高,有利于提高能量的利用率。分析了多种条件下相干合成的光强分布特性,结果表明:随机相位差小于十分之一波长时,相位差的变化对相干合成效果影响不大;当超高斯阶数大于10时对相干合成的峰值光强影响较小;随着相干发射阵列光束间距的增大,相干合成光强迅速减小,光束质量变差。得到了传输距离分别为10 m,100 m,1 km和5 km下的光强分布,表明合成的峰值光强随着传输距离的增加而由小变大,最后随着传输距离的进一步增大而衰减。最后得到了不同传输距离处的环围功率比。 相似文献
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利用准单色光干涉理论,计算了2×2平顶高斯超短脉冲激光在远场的干涉图样,分析了激光的时间部分相干性及其存在束间相位差时对相干合成的影响。计算结果表明,当单路激光输出光束线宽小于100 nm时,理想波前的远场光斑图样和峰值光强基本保持不变,当光束线宽大于100 nm时,干涉减弱衍射效应逐渐增强;光束间存在相位差时,时间部分相干性将破坏远场图样随束间相位差的周期性变化,相位差越大干涉越弱;当超过相干长度时,则为非相干合成,但1/6倍相干长度范围内,仍可视为较理想的相干合成,此时焦斑的斯特列尔比大于0.9,对超短脉冲的相干合成影响可忽略。 相似文献
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采用积分变换的技巧,推导出了径向分布高斯列阵光束通过湍流大气传输的二阶矩束宽和远场发散角的解析公式,并详细研究了大气湍流对光束扩展和方向性的影响.研究表明,相干合成情况下,子光束数N越小、径向分布半径r0越大,列阵光束扩展受湍流影响越小.相干较非相干合成时列阵光束的扩展小,但非相干合成时列阵光束扩展受湍流的影响比相干合成时的小.特别地,N足够小或r0足够大时,相干与非相干合成列阵光束的远场束宽相等.另一方面,还给出了相干和非相干合成径向分布高斯列阵
关键词:
径向分布高斯列阵光束
大气湍流
相干和非相干合成
二阶矩束宽 相似文献
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Based on the propagation law of cross-spectral density function,
studied in this paper are the coherence vortices of partially
coherent, quasi-monochromatic singular beams with Gaussian
envelope and Schell-model correlator in the far field, where our
main attention is paid to the evolution of far-field coherence
vortices into intensity vortices of fully coherent beams. The
results show that, although there are usually no zeros of
intensity in partially coherent beams with Gaussian envelope and
Schell-model correlator, zeros of spectral degree of coherence
exist. The coherence vortices of spectral degree of coherence
depend on the relative coherence length, mode index and
positions of pairs of points. If a point and mode index are kept
fixed, the position of coherence vortices changes with the
increase of the relative coherence length. For the low coherent
case there is a circular phase dislocation. In the coherent
limit coherence vortices become intensity vortices of fully
coherent Laguerre--Gaussian beams. 相似文献
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Suye Lü 《Optics Communications》2008,281(13):3514-3521
Taking the partially coherent cosh-Gaussian beam (ChG) as an illustrative example, the far-field divergence angle and directionality of partially coherent beams are studied. There are three competing physical mechanisms, i.e., the spatial coherence, diffraction and decentration, which affect the far-field divergence angle of partially coherent ChG beams. Two partially coherent ChG beams may generate the same far-field divergence angle, and partially coherent ChG beams may also have the same far-field divergence angle as a fully coherent ChG beam or as a fully coherent Gaussian laser beam if the three physical mechanisms are appropriately balanced. The consistency of the directionality of partially coherent beams expressed in terms of the far-field divergence angle and in terms of the far-field radiant intensity distribution is examined. Generally, two partially coherent beams with the same far-field divergence angle have not certainly the same far-field radiant intensity distribution. However, under certain conditions, it is possible to achieve the consistency of the directionality expressed in terms of the far-field divergence angle and of the normalized far-field radiant intensity distribution. 相似文献
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L. Dong P. Yang B. Xu X. Lei Y. Ning W. Liu H. Yan 《Applied physics. B, Lasers and optics》2011,104(3):725-733
Transforming high-order mode Laguerre–Gaussian beams in the far-field using a 127-actuator deformable mirror controlled by
a stochastic parallel gradient descent algorithm is presented. As a phase shift of half wave exists between every neighboring
lobes of high-order mode Laguerre–Gaussian beams, there are multiple lobes in the far-field. The suitable beam radius related
to the aperture size of the deformable mirror is discussed. Three system performance metrics are evaluated, and encircled
energy is preferred. Simulation results show that it is possible to compensate for the phase shifts and other phase aberrations
of a high-order mode Laguerre–Gaussian beam and achieve a single bright lobe with this approach. Transforming the far-field
intensity distribution of high-order mode Laguerre–Gaussian beams into Gaussian and super Gaussian distributions are also
investigated. 相似文献
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通过主动相位控制实现了两路固体激光器的高光束质量相干合成输出,总输出功率达到240W。建立了两路120W板条激光放大器,通过光束整形获得了高光束质量方形光斑,并实现了高占空比光束拼接,填充因子高于92.4%。研制了光轴一致性探测与控制系统,采用基于压电陶瓷的快反镜实现了光轴的高精度闭环控制,两束激光光轴一致性优于2μrad(RMS)。设计了基于现场可编程门阵列(FPGA)的相位探测与控制系统,用随机并行梯度下降算法(SPGD)锁定了两束激光的活塞相位。相位闭环后,远场光斑峰值提高到开环状态的1.7倍,为理想值的84%。合成光束主瓣包含67%的激光总能量,光束质量(BQ)为1.1。 相似文献
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We demonstrate experimentally the application of a phase error detection method in the coherent beam combination (CBC) of a laser array. The method is based on the Hartmann micro-lens array. Both the piston and tilt errors can be detected and corrected simultaneously by combining this method with adaptive optics-correcting technology. The far-field intensity pattern of the combined beam has high energy concentration and good beam quality. The power encircled in the main lobe of the far-field pattern is 41.3%, and the contrast of the pattern reaches 81.8%. Experimental results show the great potential of the Hartmann phasing method for use in the CBC of a large number of laser beams. 相似文献