四种解析解设计的短程透镜卷边对损耗的影响

根据光波导短程透镜母线曲率半径与光传输损耗的关系,利用数值计算的方法,通过计算不同母线参数条件下,四种解析解设计的短程透镜母线曲率半径,研究比较了短程透镜卷边对其损耗的影响,得出了短程透镜损耗与其有效区半径关系的曲线图,发现透镜凹面半径一定时,有效区半径越小,即卷边越大时,光传输损耗越小;短程透镜的解析改进解和最优解设计的透镜卷边存在曲率奇点.并由此得出了四种解析解设计的短程透镜有效区半径选取原则及其满足低损耗条件的取值范围.     

Focal shift of apodized truncated hyperbolic-cosine-Gaussian beam

Focal shift of hyperbolic-cosine-Gaussian beams induced by pure phase apodizer was investigated theoretically. The pure phase apodizer consists of three concentric zones: center circle zone, inner annular zone and outer annular zone. And the phase variance of the inner annular zone is adjustable. Results show that intensity peak moves far from optical aperture and then shrinks sharply for certain radii of zones with increasing phase variance of the inner annular zone. Simultaneously, one new intensity peak occurs near optical aperture, moves far from the optical aperture, and then becomes intensity maximum peak, and repeats the evolution process of the former intensity peak. Tunable focal shift occurs with focal switch. Decreasing the phase variance can change the move direction of the intensity peaks. In addition, the maximum distance between the two intensity peaks can be altered by beam parameters of cosh parts, and the distance value increases and then decreases with increasing beam parameters of cosh parts for certain radii of zones. Tunable focal shift is also discussed to construct optical tweezers.     

Focal depth and focal splitting of truncated hyperbolic-cosine-Gaussian beam induced by phase plate

Focal depth and focal splitting of hyperbolic-cosine-Gaussian beams induced by a phase plate were investigated. The pure phase plate consists of three concentric zones: a center circle zone, an inner annular zone and an outer annular zone. The phase variance of the inner annular zone is adjustable. Simulation results show that the focal depth can be adjusted by changing the radii of zones. With the increase of the inner radius of the outer annular zone, the focal spot broadens along the optical axis and splits into two peaks. Then the two peaks combine back into one peak. There are two critical values for the inner radius of the outer annular zone, at which focal spot changes sharply. The tunable range of the focal depth varies considerably. The phase variance of the inner annular zone affects focal depth also; when the phase variance is π, the effect attains maximum. The parameters of cosh parts of the beam affect both focal splitting and focal depth evidently; focal splitting disappears with increasing parameters of cosh parts, and focal depth increases with increasing the parameters of cosh parts in both the low and the high numerical-aperture optical systems.     

Improving the resolution of a solid immersion lens optical system using a multiphase Fresnel zone plate

We propose a method to improve the resolution of near-field optical system with a solid immersion lens by using a multiphase level Fresnel zone plate. The analyses are based on scalar angular spectrum theory. The results show that the multiphase Fresnel zone plate can not only decrease the spot size but also decrease the sidelobe intensity and enhance greatly the diffractive efficiency compared with annular amplitude filter or binary 2-, 3-, 4-zone phase filter.     

High depth of focus by combining annular lenses

In some technological applications, optical systems that produce a high depth of focus and superresolving transversal responses are required. In this paper we present a pupil design consisting in a phase pupil with binary amplitude, that added to a conventional optical system, can accomplish these goals. The pupil function is characterized by a complex amplitude that consists basically in combining two annular lenses with different focal length. Meanwhile the central portion of the pupil has an amplitude equal to 0, the external portion is modulated with two quadratic phases each one covering an annular zone. One of the phases corresponds to a convergent lens and the other to a divergent lens. The effect on the incident wavefront is to redirect the light in front of and behind the best image plane (BIP) producing a widened focus. The evolution of the transverse gain for the extended focus is also studied. Experimental results are given, and they confirm the extended focus and the superresolving behavior of the proposed pupil function.     

基于球面透视投影约束的全景环形透镜畸变校正

全景环形透镜将折反射面集成到一起,能无扫描地瞬时得到围绕光轴的360度超大视场,在机器人导航、视频监控和虚拟现实领域得到了广泛的应用.其成像机理是将围绕光轴的视场二次反射投影到环形平面上,图像存在严重的切向和径向畸变.本文根据全景环形透镜的特点采用基于球面透视投影模型对图像进行校正.首先建立含有畸变参量的全景环形透镜校正模型,将空间直线点映射为球面点,然后使用遗传算法将球面点拟合为球面上的最佳大圆,求出变形校正参量,进而校正全景环形像.仿真和真实图像实验表明,环形图像的切向和径向畸变得到了很好的校正.     

A study of the optical transfer function for annular binary filters

The annular binary pupil filters consist of two transparent annuli obstructed by an annular mask. The optical transfer functions for them are analytically derived under paraxial approximation, and three- and two- as well as one-dimensional numerical plots are presented. It is shown that by changing the parameters of transparent regions it is possible to improve the axial resolution whilst the transverse resolution remains unchanged, compared with an annular lens. Results indicate, as is well known, that this kind of filters can be applied to three-dimensional confocal microscopy.     

A simple experimental method to generate partially coherent optical bottle beam

An experimental study is carried out to investigate a special kind of three-dimensional intensity distribution of a partially coherent optical beam known as optical bottle beam produced by using an annular aperture and lens combination (Lens Aperture System). In this paper, we are demonstrating the experimental results of our observations. The investigation also includes the effects of coherence modulation and central obstruction of the annular aperture (used in Lens Aperture System) on the resultant partially coherent optical bottle beam. The method discussed in this paper is simple and cost effective.     

Focusing properties of the hyperbolic-cosine-Gaussian beam induced by phase plate

Focusing properties of hyperbolic-cosine-Gaussian beam induced by phase plate were investigated theoretically in this Letter. The phase plate consists of three concentric zones: center circle zone, inner and outer annular zones with 0, π, 0 phase variations, respectively. Numerical simulations show that the evolution of the focal shape is altered considerably by changing the radii of zones and the decentered parameters in cosh parts of the light beam. Increase inner radius of the outer annular zone, focal spot broadens along optical axis, splits into two peaks, and then the two peaks combine back into one peak. In this process, the focal depth increases and then decreases three times, so three focal depth peaks occur. And the distance between the two peaks for bigger inner radius of outer annular zone is very small. With decreasing decentered parameters in cosh part of the beam, position of the three focal depth peaks shift toward to small radius, and the peak values also fall simultaneously.     

一种用于大气探测的紫外成像仪光学系统设计

提出了一种将全景成像系统应用到大气临边探测的光学系统设计方案。首先考虑到特殊的工作波段以及创新性应用,根据应用技术指标,在传统全景环形透镜的基础上,结合探测器尺寸限制,精细调整四个球面的曲率半径,以便得到最佳光学传递函数。然后基于像差理论设计中继镜组系统,补偿全景环形透镜产生的像差,采用折射率n以及阿贝常数ν不同的双分离的正负透镜组合,负透镜采用熔石英,正透镜采用氟化钙,从而使色差最小。最后运用CODE-V光学设计软件对系统进行优化,列出重要的公差参数,为后续加工装调提出要求。优化结果表明,光学系统在各个视场的光学传递函数均达到了0.7以上,各视场能量集中度为80%的弥散圆直径均小于11 μm,完全满足设计指标要求,也证明了将全景环形成像系统应用到紫外波段大气临边探测的方案是可行的。     

光束自聚焦的矢量理论研究

基于矢量非傍轴非线性Schr-dinger方程,利用调制理论研究了光束的自聚焦特性,比较了非零电场散度项和非傍轴项在消除自聚焦崩塌方面的贡献。结果表明,引入两项之一都可使光束聚焦到一有限宽度后开始散焦,然后又自聚焦,如此作聚焦-散焦的周期性循环。但是,在光束自聚焦点附近,非零电场散度项的作用要强于非傍轴项。     

Transverse Properties of Light Distribution in the Focal Plane for Rectangular Annular Pupil Plane Filters

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Transverse Properties of Light Distribution in the Focal Plane for Rectangular Annular Pupil Plane Filters

Rectangular annular pupils are designed. The transverse intensity distribution and the superresolving characteristics of the pupils in the focal plane are analyzed. The influences of total annular zone numbers and the central core magnitude on the light efficiency (the Strehl ratio S), the superresolving power (the normalized spot size G) and the intensity of sidelobe are studied in detail. The properties are different for two kinds of pupils: one with total odd annular zone numbers and another with total even annular zone numbers. Circular annular pupils are also discussed and the comparison between them is given.     

Focusing of flattened Gaussian beams by an annular lens

Focusing properties of flattened Gaussian beams (FGBs) passing through an annular lens is studied based on the Collins formula. It is found that the on-axis irradiance distributions of focused FGBs are unsymmetrical with respect to the geometrical focal plane even for large values of Fresnel number F_w associated with the beam, so that there exist focal shifts in general. Detailed numerical results show the dependence of focal shifts on the beam and system parameters. Focal shifts of FGBs by a lens without central obscuration and focal shifts of Gaussian beams by an annular lens can be treated as special cases of the obscure ratio =0 and beam order N=0, respectively. Furthermore, focal shifts of plane waves by an annular lens can also be treated as a special case of N=0 and F_w→∞.     

混合复消色差透镜组的设计原理

通过对混合复消色差透镜组的像差分析导其结构参数的求解方程，根据计算机模拟结果发现，二元光学元件以正透镜为基底和以负透镜为基底时单色像差状况大体相当，但以正透镜为基底时色球差要小得多。     

用于中小型飞行模拟器的球带幕投影镜头的光学设计

针对现有沉浸式飞行模拟器进一步小型化和低成本化的需求,设计了一款应用于中小型飞行模拟器的球带幕投影镜头。论文确定了投影方案中各部件(球带幕、投影机、投影物镜)的关键参数,设计的球带幕投影镜头具有172°的视场角和6∶1的反远比,将一台装有该镜头的投影机置于银幕上沿就可以将画面投满整个球带幕。文中给出了大视场、大反远比光学系统的构造方法,对大视场非相似成像系统中的畸变、场曲和相对照度进行了分析和讨论,并给出了改善照度均匀性的有效途径。该镜头以8片透镜的低成本结构满足了4 k分辨率的高质量投影需求,在奈奎斯特频率185 lp/mm处全部视场的MTF值均达到了0.4以上,且具有良好的工艺性。     

激光辐照猫眼光学镜头时的反射特性机理研究

运用矩阵光学理论以及将硬边光阑窗口函数展开为有限个复高斯函数之和的方法, 对激光束辐照猫眼光学镜头时产生的猫眼效应机理进行了理论推导. 通过数值计算对猫眼效应的反射规律进行了分析, 并利用532nm激光辐照一个变焦范围为12—72mm的光学镜头进行了猫眼效应的实验验证, 从而得出了猫眼效应反射光特性与入射激光参数以及猫眼光学镜头的口径、焦距、离焦量等基本参数之间的关系. 研究表明, 猫眼效应反射光特性与猫眼光学镜头参数和入射激光参数密切相关, 且当猫眼光学镜头位于近场和远场的情况有很大不同. 根据入射光束 关键词： 猫眼光学镜头 猫眼效应 高斯光束 反射特性     

Tight focus of an azimuthally polarized and amplitude-modulated annular multi-Gaussian beam

We investigate the focusing properties of an azimuthally polarized and amplitude modulated annular multi Gaussian beam by a high numerical aperture (NA) lens based on vector diffraction theory. We observe that our proposed system generates a subwavelength focal hole of 0.46λ having large uniform focal depth of 36λ without any annular obstruction. This kind of nondiffracting focal hole is called dark channel, which may have applications in atom optical experiments, such as with atomic lenses, atom traps, and atom switches.     

Improved axial resolution in confocal fluorescence microscopy using annular pupils

The axial image of a thick fluorescent layer is studied in a confocal microscope consisting of either circular or annular pupils. The response for circular pupils is sharper than that for annular pupils if a small pinhole detector is used. But when the size of the pinhole is larger than a certain value, the response in the latter case can become sharper than that in the former. This result implies that for a given detector of finite size, axial resolution in confocal fluorescence microscopy can be improved when an annular lens is used. Our experimental results qualitatively demonstrate the theoretical prediction. The strength of optical sectioning and the axial cross-section of the three-dimensional optical transfer function are also derived from the measured data.     

Changes in the intensity distribution and polarization of non-uniformly polarized beams focused by a spherically aberrated lens with annular aperture

Based on the generalized Huygens-Fresnel diffraction integral and beam coherence polarization (BCP) matrix formulation, the focusing properties of a type of non-uniformly polarized (NUP) beam through a spherical aberrated lens with annular aperture are studied. The dependence of focal shift, intensity distribution, power in the bucket (PIB) and degree of polarization on the spherical aberration coefficient, obscure ratio and polarization parameters is illustrated numerically. The focusing of NUP beams by a spherically aberrated lens with circular aperture is treated as a special case, where the inner radius of the aperture is equal to zero.