关于失调矩阵的讨论

本文讨论了光学元件失调矩阵的计算方法以及有关的性质。     

The influence of nonparaxiality on the spectral behavior in Young's experiment illuminated by partially coherent light

Starting from the Rayleigh--Sommerfeld diffraction integral, this paper studies the spectral behavior in Young's experiment illuminated by nonparaxial partially coherent light and compares with the paraxial case, where the influence of nonparaxiality of partially coherent light on the spectral shifts and spectral switches is stressed. It is shown that there is a spectral shift in the nonparaxial case relative to the paraxial one and the critical position changes, at which the spectral switch occurs. The ratio of the waist width to the central wavelength w₀/λ₀ and relative spatial correlation length \De affect the spectral difference. The smaller w₀/λ₀ is, the larger the difference between the nonparaxial and paraxial results appears. The effect of relative spatial correlation length Δ is relatively small.     

Can two partially coherent cosh-Gaussian beams generate far fields with the same spectral degree of coherence？

Taking partially coherent cosh--Gaussian (ChG) beams as an example of more general partially coherent beams, we have studied the spectral degree of coherence of partially coherent ChG beams in the far field. It is shown that, unlike Gaussian Schell-model (GSM) beams, in the strict sense there do not exist two partially coherent ChG beams which can generate far fields with the same spectral degree of coherence. However, under certain conditions it is possible to find two partially coherent ChG beams with the same spectral degree of coherence in the far field.     

Propagation of ultrashort pulsed beams in dispersive media

Starting from the Rayleigh diffraction integral, the propagation equation of ultrashort pulsed beams in dispersive media is derived without making the paraxial approximation and slowly varying envelope approximation (SVEA). The spatiotemporal properties of ultrashort pulsed beams in dispersive media, such as spectrum redshifting, narrowing and pulse distortion are illustrated with pulsed Gaussian beams. It is stressed that the “antibeam“ behaviour of ultrashort pulsed beams can be avoided, if a suitable truncation function is chosen.     

Effect of astigmatism on spectral switches of partially coherent beams

A detailed study of the spectrum of partially coherent beams diffracted at an astigmatic aperture lens is performed. Considerable attention is paid to the effect of astigmatism on spectral switches of polychromatic Gaussian Schell-model beams. It is shown that the spectral switch can also take place in the vicinity of intensity minimum in a geometrical focal plane for the astigmatic case, but the astigmatism of the lens and the spatial correlation of the beam affect the critical position u_c, spectral minimum S_{min}, and transition height Δ of spectral switches.     

LD侧泵浦Nd：YAG板条双程功率放大器初步研究

 对二极管激光侧泵浦Nd：YAG板条双程功率放大器进行了初步的研究,给出了激光器的数值模拟结果,建立了二极管侧面泵浦Nd:YAG板条激光主振荡-多程放大(MOPA)系统;在100Hz重复频率时,实验获得单脉冲能量为51.9mJ的输出,光束质量M ²小于2,脉冲能量起伏小于2%, 实验结果与数值计算结果相符合。     

用K参数描述光强陡峭度的有效性研究

光束光强分布的陡峭度或平整度通常可用陡峭度参数(K参数)来描述。以双曲余弦-高斯光束、贝塞尔函数调制的高斯光束和平顶高斯光束3种光束为例,给出了详细的数值计算和物理解释。研究表明,K参数只适用于描述呈钟形光束剖面的陡峭度,但不适用于有强衍射旁瓣、强调制或有中心凹陷的光束。     

大气激光束漂移的实验研究

为了研究激光束在大气中的漂移情况,对激光束在大气中的传输做了实验研究。采用电荷耦合器件CCD成像技术对光斑的漂移情况进行了测量。对光斑漂移在水平和垂直方向的变化进行了实验研究,并分析了横向风对光束漂移的影响,得到了在不同时刻以及不同传输距离情况下光束漂移情况的实验结果。结果表明,光束随传输距离的增加,垂直和水平方向的漂移量逐渐趋于一致。     

部分相干厄米-高斯光束杨氏实验中的光强分布

将杨氏干涉实验作为双缝衍射现象处理,以部分相干厄米-高斯(H-G)光束为例,研究分析了多模部分相干光的杨氏双缝干涉光强和干涉条纹可见度的空间分布。数值计算说明,多模部分相干光束的空间相干参数、模阶数和缝遮拦比对衍射场中光强的空间分布(干涉花样)都有影响。当多模部分相干光的阶数为奇数时,轴上光强与光束的相干性会出现相消干涉;当多模部分相干光的阶数为偶数时,轴上光强与光束的相干性会出现相长干涉等。     

两种M~2因子实验测量方法的比较

为了从实验上分析和验证H-S传感器测量M2因子方法,对使用双曲线拟合法测量M2因子和H-S传感器测量M2因子做了详细的实验研究,且对实验结果、实验误差进行了比较与分析。研究表明:当H-S波前传感器透镜组足够多,重构误差较小,选取合适的泽尼克多项式阶数时,H-S波前传感器一次测量法得到的光束的M2因子与传统方法测得的M2因子值基本相当。与双曲线拟合法相比,H-S传感器法适用范围小,但是当满足测量条件时,H-S传感器法更便捷。