圆锥透镜对偏轴球面波光束的衍射模式

球面波入射圆锥透镜产生的出射光束中心光斑直径较小且焦深长，适合通讯领域长距离测量和准直。针对实际操作中球面波光束入射时很可能与圆锥透镜的中心轴线发生偏移或倾斜，使衍射光场发生变化，着重研究圆锥透镜对偏轴球面波光束的衍射模式，并通过衍射理论和稳相法分析，研究其径向衍射光场的分布特性。使用半径为15mm，底角为1°的圆锥透镜进行计算机仿真和实验，最后将实验结果与理论分析和仿真结果相比较，证明球面波的曲率半径和出射光束的传输距离越小，偏轴对衍射模式的影响越小。该研究结果表明：在激光通讯等长距离通信中，使用曲率半径小的球面波光束代替平面波入射圆锥透镜，不仅可以扩展焦深，还可以降低偏轴对测量的影响。     

一种球面透镜波前畸变的绝对检测方法

球面透镜的透射波前畸变是影响激光驱动器光束质量的重要参数。采用移相干涉仪检测球面透镜波前畸变时,测量结果的精度受限于标准球面镜头和后置平面反射镜的精度。然而,现有的绝对检测技术仅适用于反射元件。为了满足球面透镜波前畸变的高精度检测需求,提出了一种适用于球面透镜透射波前的绝对检测方法:三位置 平移相减法。详细介绍了三位置 平移相减法的原理,对其进行了模拟仿真和实验验证。仿真结果显示:三位置 平移相减法的仿真误差为10 nm~13 nm,达到高精度测量的理论要求;实验结果表明:三位置 平移相减法可以有效地减小前标准球面镜头和后置平面反射镜对测量结果的影响,该方法对球面透镜的加工和装调具有很好的指导意义。     

The intensity distribution of hollow Gaussian beams focused by a lens with spherical aberration

We developed an expression that describes the hollow Gaussian beams (HGBs) passing through a spherically aberrated lens by using the Collins formula. The radial intensity distribution in both spherical aberration SA free lens, lens that exhibits relatively large in both positive spherical aberration PSA, and negative spherical aberration NSA is calculated. Numerical calculations are made and the results show that the PSA and NSA have a strong influence on the intensity distribution especially at the focus. The study showed remarkable results for which there is no hollow Gaussian beam at a large NSA along the optical axis at the focus. In addition, we found that the DSS, and w_r of focused hollow Gaussian beams in the focal region depend not only on the beam radius, and beam order; but also on the spherical aberration.     

高库仑量大电流两电极气体火花开关研究

设计了一个两电极气体火花开关，开关的主体部分仅包括阴极、阳极两个主电极，以及金属外壳和绝缘支撑外壳，两电极结构取消了触发极，消除了由于触发极烧蚀影响开关寿命的问题。开关设计工作电压23 kV，单脉冲能量1.2 MJ，峰值电流300 kA，单次脉冲电荷转移量110 C。初步试验阶段开关工作电压达到15 kV，开关的通流180 kA，电荷转移量为47.85 C。开关触发性能可靠，电极烧蚀均匀。     

附加球面相位引致Airy光束在单轴晶体传输时的两次镜像演化

利用单轴晶体光束传输理论,求得了具有附加球面相位Airy光束在单轴晶体中的传输公式.数值模拟计算结果表明,线偏振附加球面相位Airy光束在晶体中传输时仍为线偏振,但不是传输不变的.粗略地讲,具有附加球面相位的Airy光束在晶体中传输时,近场是传输不变的;而在由晶体寻常与非寻常折射率和球面半径共同确定的两个特定传输距离处,传输光束转换成了取向不同的Gaussian-Airy光束,且高斯依赖的束宽度敏感地与截断因子相关;而当光束依次穿过此两位置时光斑花样先后相对于两横向轴平面做镜像演化,且镜像演化顺序也与晶体寻常和非寻常折射率相对大小密切相关,其总的效果是远场强度花样能恢复原样但花样取向产生了关于对过横平面二、四象限平分平面的镜像演化.这些结果表明,通过恰当选择晶体材料(即折射率)和附加球面相位的半径R,可以调控光束花样的形状、取向及表征各向异性材料的相关性质.     

透镜初级球差的横向剪切干涉条纹研究

利用玻璃平行平板构成简单的横向剪切干涉仪可以观察到单薄透镜形成的准直光束的剪切干涉条纹,由干涉条纹分布求出对应的几何像差和离焦量.用焦距为190 mm的单薄透镜做实验,实验结果与计算机模拟结果符合,说明可以从剪切干涉条纹的分布求出透镜的轴向调整误差和初级球差.     

Influences of pump beam distribution on thermal lensing spherical aberration in an LD end-pumped Nd:YAG laser

A numerical investigation is made on the thermal lensing and spherical aberration effect in an LD end-pumped Nd:YAG laser. Based on the finite element method (FEM), the laser rod temperature distribution is calculated and the focal length of the thermal lens is deduced, the influences of pump beam on the thermal lensing spherical aberration are mainly studied. The results show the thermal lens which focal length varied with the radial coordinate r is not an ideal lens. Given the heat dissipation boundary conditions, the radial dependent focal length will be shortened when the pump power raised or the waist radius of the pump beam reduced, meanwhile the radial differences of the focal length will decrease when the pump power increased. For a Super-Gaussian profile pump beam, the higher the exponent number, the more similar to flat top the pump beam is, and the less the radial differences of the focal length are.     

Influence of spherical aberrations on the performance of dynamically stable resonators

Spherical aberrations of thermal lens of the active media are severe when the solid state lasers are strongly pumped. The aberrations influence the mode profile, the diffraction loss, the output power and other laser beam properties, especially for a dynamically stable resonator with large TEM₀₀-mode volume. Self-consistent modes in a resonator with aberrations are calculated using Fox-Li diffraction iterative algorithm. There are side lobes with the fundamental mode when the spherical aberration is introduced, hence the beam quality is deteriorated. The calculated results agree well with the experimental data. The beam filling factor plays an important role in the design of a laser system. The optimum value of the beam filling factor should be determined by the experimental results according to the spherical aberration effect.     

热透镜的球差效应对大基模体积激光谐振腔模式的影响

固体激光器在强抽运的条件下,激光晶体热透镜的球差效应是不容忽视的,尤其是在大基模体积的动态稳定腔中,会影响谐振腔的振荡模式,进而影响腔内损耗和输出功率.通过Fox-Li的衍射迭代算法,分析了谐振腔的自再现模,表明在热透镜球差效应作用下,基模的光强分布出现了旁瓣,并由此带来了光束质量的下降,最后通过实验结果验证了理论分析,指出光束填充因子是激光器设计的一个重要因素,其最佳值需要根据球差效应的强弱,通过实验的方法来确定. 关键词： 热透镜 球差效应 谐振腔模式     

Scattering of a Gaussian Beam by Stepped Index Luneberg Lens

The scattering and focusing characteristics of a Gaussian beam with phase distribution is studied by a stepped index Luneberg lens. A model experiment was performed using a six-layer spherical lens. Two kinds of beams, that is, broad and narrow beam are examined for the incident Gaussian beam. We find that focusing effect of a narrow beam is wholly lower than that of a broad beam. The focal point is also shifted toward outer of sphere because of phase lag for the beam source. The spot size equals almost the wavelength for the various beam parameters.     

标准球面透镜的几何特性与误差分析

标准球面透镜是斐索型干涉仪的核心器件,综述标准球面透镜的几何特性和误差。分析标准球面透镜在干涉照明光路和成像光路中的作用,重点介绍并实验验证了球面干涉成像的R-sinθ几何特性关系模型,给出了采用Q非球面实现非球面分裂的新型设计方法,以及2片式非球面标准球面透镜结构的实例,概述了针对小F数标准球面透镜球面干涉腔中的待测球面调整误差和移相空间非均匀性误差的研究成果,介绍了校正球面干涉腔中误差的波面差分算法,指出在近标准球面透镜焦点位置测量球面时的回程误差影响,从物像共轭关系角度解释了近焦点位置回程误差较大的原因,比对分析了标准球面透镜的透射波前与斜率对回程误差的影响。提出了在设计标准球面透镜时需注意的几何特性关系,以及使用标准球面透镜时易产生的误差和相应的抑制方法。     

Fourth order correction to a Gaussian beam focused with a parabolic index lens

We formulate the fourth order correction to a paraxial Gaussian beam propagated along the axis of symmetry of a parabolic index lens. First we examine the evolution of a complex-source-point spherical wave (equivalent paraxially to a Gaussian beam) through the lens in a two-dimensional xz plane. Taking into account the terms of up to fourth order in aperture variables, we find a ray-optical solution to the exit beam that is represented in terms of aberration function. We also analyze the effect of the lens aberration exerted on the degradation in the quality of a Gaussian beam. The fourth order-corrected wave function derived here may be used to evaluate the quality of a Gaussian beam focused with a parabolic index lens. Further it may be applied to the case of an orthogonal system in which the index variations are different in the xz and yz planes.     

离轴球形粒子对高斯波束的散射光通量的计算

利用矢量球谐函数展开的方法,研究了离轴球形粒子对椭圆高斯波束的散射。根据其远区散射场的形式,得出了归一化散射场的斯托克斯参量(散射强度)与颗粒直径、折射率以及散射角的关系。建立了计算离轴球形粒子对高斯波束散射通量的解析模型,计算了散射光在任意散射方向上的光通量,得到了前向任意立体角内散射通量的计算公式,为激光散射探测提供了理论依据。     

High aperture focusing through a spherical interface: Application to refractive solid immersion lens (RSIL) for subsurface imaging

The effects of on-axis spherical aberration and defocus on focusing across a spherical interface between two materials of mismatched refractive index are discussed. A vectorial integral representation for high aperture focusing in this configuration is formulated and an analytical expression for the spherical aberration function is derived. Numerical simulations are performed to analyse the effects of the spherical interface on both the transverse and axial intensity profiles. The results from these numerical simulations are important industrially in understanding the resolution enhancements from solid immersion lens technology, as well as being of more fundamental interest in calculating the distribution at the focal plane under different solid immersion lens configurations.     

Focusing of a singular beam in the presence of spherical aberration and defocusing

Focusing of a singular beam by a lens in the presence of spherical aberration and defocusing is studied by using Fresnel–Kirchhoff diffraction integral for two different values of topological charge. Results of intensity distribution and encircled energy are plotted for defocused observation planes. Spherical aberration spreads the dark core and reduces the intensity at maxima. The results have been verified by the optical transfer function (OTF) approach.     

Mathematical simulation of the technology and properties of gradient spherical lenses

The possibilities of improving the optical characteristics of spherical lenses with an axial refractive index gradient are analyzed. The refractive index profile obtained as a result of the Fickian-diffusion exchange of molecules through a flat boundary of the medium is considered. It is shown for the specific polymer system polydiallyl isophthalate plus polymethyl methacrylate (PMMA) that the spherical aberrations can be reduced by almost an order of magnitude in comparison to the aberrations of a homogeneous lens of the same geometric shape made from PMMA. Zh. Tekh. Fiz. 68, 70–73 (October 1998)     

Focusing of a vortex carrying beam with Gaussian background by a lens in the presence of spherical aberration and defocusing

Diffraction pattern formed by a lens for a vortex containing truncated beam with Gaussian background, and in the presence of spherical aberration and defocusing has been studied by Fresnel–Kirchhoff diffraction integral. For the study, two different values of topological charge are selected. Compensation of aberration in the presence of appropriate value of defocusing is investigated. Presence of spherical aberration results in an increase in the size of the dark core of the diffraction pattern. Results are also presented for the encircled energy. Some results are also presented for the influence of truncation parameter of the beam, on the point spread function at different observation planes.     

透镜焦距及球面曲率的测量

概述目前透镜焦距及球面曲率半径的测量方法，介绍透镜焦距及球面曲率半径的准直光束补偿测量法的原理，指出该方法的关键是对补偿光束准直性的检测，提出一种用准直光束补偿和横向错位进行干涉测量透镜焦距及球面曲率的新方法。     

基于Zemax的He-Ne激光光束聚焦物镜的设计

 为了得到一个合理的He-Ne激光光束聚焦物镜,采用以正前凸型为基础的高折射率双片结构,应用Zemax软件进行优化设计,获得了弥散斑直径为0.002mm的He-Ne激光聚焦物镜,该镜头只需校正轴上点球差。实验结果表明：设计的镜头比低折射率单片透镜得到的弥散圆直径更小,达到0.0019mm,球差被控制在-0.05mm～+0.05mm范围内,MTF曲线所围面积变大,中心点亮度增高,符合实际需要。     

高斯光束经过负球差透镜的聚焦

本文讨论高斯光束经过负球差透镜的聚焦，得到了聚焦光场轴上点的光强分布的表示式，并对其进行数值计算。数值计算结果表明，在负球差的情况下，得到光强的最大点位置（最佳聚焦点）相对于无球差情况，往透镜方向移动，并且，最佳聚焦点的光强较无球差时大，当Ｎｗ＝１，Ｎａ＝５，ｋＳ１＝－０．２时，得到的最佳聚焦点的光强是无球差时的１．３４倍。本文还讨论了透镜的菲涅尔数对聚焦光场分布的影响。结果表明，当透镜的菲涅尔数小于１时，球差对高斯光束的聚焦的影响可以忽略。