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1.
To increase recording density in an optical disk system, a two-lens system which enlarge its numerical aperture (NA) has been developed. When NA becomes larger, however, the spherical aberration due to disk thickness error increases. We propose an optical pickup with a spherical aberration compensator using nematic liquid crystal (LC). Our LC device is composed of two LC cells each of which has X and Y stripe electrodes, respectively. We discussed how the spherical aberration due to the disk thickness error can be compensated by combination of two crossed cylindrical phase distributions induced by the LC cells, and confirmed the compensation effect in a design example by simulation. We have also fabricated the crossed stripe LC device actually, and have obtained the experimental result which shows that amount sufficient to compensate the aberration is achieved. 相似文献
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传统整流罩为半球形或半球形的一部分,产生的空气阻力较大,不利于武器飞行速度的提高。基于空气动力学性能的考虑,采用共形整流罩的光学技术被提出。文章描述了二次曲面共形整流罩外表面、内表面的设计方法及面型表达式,通过在CODEV中建立共形整流罩的扫描成像模型,应用Zernike多项式分解法研究了不同长径比、边缘斜率、口径比和回转中心位置对离焦像差(Z4)、像散(Z5)、彗差(Z8)和球差(Z9)的影响规律。研究结果表明:二次曲面共形整流罩引入的离焦像差、像散、彗差和球差均随着长径比、边缘斜率和口径比的增加而增大,但对成像系统回转中心的位置不敏感。因此,在满足武器的空气动力学性能条件下应尽量减小长径比、边缘斜率和口径比,回转中心的位置主要根据结构需要进行设计。 相似文献
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Imaging by two concentric spheres is studied by geometrical method. As the system is symmetric with respect to the common center of curvature, peripheral aberrations, namely coma, astigmatism, and distortion, do not appear. The imaging surface is a sphere that shares the center of curvature with two mirrors. As we solve the zero spherical aberration condition for imaging of an object at infinite distance, the golden section number appears as the ratio of the distance between two mirrors and the radius of the primary mirror. For imaging of an object at finite distance, we have to increase the radius of the second mirror. This system also has no peripheral aberrations. Making the object surface spherical, we can obtain a flat image surface. As the spherical aberration is zero in the original system, spherical aberration, coma, and astigmatism remain zero when the object surface is curved. 相似文献
4.
Susumu Sato 《Optical Review》1999,6(6):471-485
Liquid Crystal (LC) lens cells with variable focusing properties are fabricated using nematic LC materials and applicable to optical devices, and our recent work on these cells is described. First, the LC lens cells are prepared using lens-shaped substrates coated with transparent electrodes. Their focal length can be continuously varied between the values for an ordinary ray and an extraordinary ray by changing the voltage passing across them. Methods of improving properties and some applications of the lens-shaped LC lens are briefly described. The lens properties of these cells with plane-paralleled structure are then demonstrated, where the refractive index is graded to a quadratic distribution resulting from an axially symmetric non-uniform electric field. LC cells with axially distributed tilt angles are constructed using a pair of circular hole-patterned electrode substrates and very small LC lens (LC microlens) with variable focusing can be fabricated. Optimizing the electrode structure, device parameters, and material parameters of the LCs, excellent focusing properties can be obtained. The properties of the LC microlens are improved by using the polymer stabilization technique. The LC microlens with a divided electrode structure shows three-dimensional beam steering and focusing properties, and the astigmatic aberration caused by the molecular orientation effect can be compensated. Applications of the LC microlens to optical devices and systems are introduced. 相似文献
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为了降低紫外高分辨率罗兰光栅的像散对光谱像高展宽的影响,提出了在罗兰圆上使用球面波非对称曝光设计思路。推导完全校正离焦和子午彗差的表达式,讨论了多种罗兰光栅记录结构的局限性,优选适合校正紫外高分辨率罗兰光栅的优化方法。通过全息光栅像面展宽表达式, 指出像散和弧矢彗差是影响光谱像高的主要因素,并分配了两者的优化权重。利用这种优化思路,设计了工作波段110~200 nm紫外高分辨率罗兰光栅,同时对比分析了传统光栅的像差系数和像高变化规律、像面结构和光谱分辨率。结果表明,和传统罗兰光栅分辨率处于同一数量级的情况下,所设计光栅光谱像高由25 mm降低到1.5 mm,谱面能量集中度有显著的提高。 相似文献
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根据波像差理论,推导了光学合成孔径成像系统单个子孔径存在各种像差时波面方差与子孔径数(N)的关系。推导结果表明,piston误差对系统的影响最大,其次是离焦误差、倾斜误差、球差、彗差和像散。运用离焦误差对piston误差、球差和像散进行像差平衡,其效果显著,特别是球差引起的波面方差下降90%。系统各项像差系数随子孔径数的增加而降低;当子孔径数大于6时,各像差系数变化缓慢。根据瑞利判据,计算N(N≤6)个子孔径合成系统的像差允限和相应的3孔径系统的斯特列尔比。 相似文献
8.
We examine the effects of third-order aberrations exerted on the irradiance of image that is observable in a coherent self-imaging system. Both spherical aberration and astigmatism degrade the visibility of the image of a sinusoidal-type grating as well as blur the outline of the image of a rectangular-type grating. Coma laterally shifts the image of a sinusoidal-type grating on the image plane as well as changes a rectangular-type pattern into an asymmetrically blurred pattern. According to our analysis, the self-image of a high-density grating with a period of two times the optical wavelength is not at all affected by spherical aberration. In general a self-imaging system can always be corrected for astigmatism by shifting the image plane in its normal direction. We show that the self-image with defect can be well explained by taking the third-order aberrations and the focus-shift aberration into consideration. 相似文献
9.
T. Tchen 《Technical Physics》2002,47(6):660-665
Focusing of a spherical wave in the well-known Johann scheme is considered theoretically. An analytical formula for the size of the crystal bent surface reflecting radiation in the Johann scheme is derived. The intensity distribution near the focus is found. The spherical aberration of the diffracted beam is analyzed. Back scattering is shown to minimize the aberration. Spectral characteristics of an Johann spectrometer are discussed. The focusing of a spherical wave by a crystal bent into a logarithmic spiral is considered. It is shown that the Johann scheme is a specific case of a logarithmic spiral. 相似文献
10.
Expressions for third-order aberration in the reconstructed wave front of point objects are established by Meier. But Smith,
Neil Mohon, Sweatt independently reported that their results differ from that of Meier. We found that coefficients for spherical
aberration, astigmatism, tally with Meier’s while coefficients for distortion and coma differ. 相似文献
11.
《Current Applied Physics》2015,15(3):292-297
Polymer dispersed liquid crystal was synthesized by combining a UV curable polymer and a nematic liquid crystal. Optimized conditions for the optical properties of the PDLC were found to be the concentration ratio of LC and polymer at 7:3, UV curing time of 18 min, and the thickness less than 25 μm. In the case of the high LC concentration (≥70%) sample, the amount of liquid crystal segregated in the polymerization process was enough to form a spherical shape of droplet, and the threshold driving voltage was reduced. The response time for the turn-on process was nearly independent of the concentration, while the turn-off process was almost proportional to the concentration. From microscopic image and UV–visible spectrum analysis, the relation between LC droplet morphology and optical properties were explained. 相似文献
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本文从泽尼克一高斯国多项式出发,讨论了三种初级象差(球差、营差、象散)在平衡及未平衡状态下的标准偏差同衍射孔半径与高斯光束半径之比α的关系.最后讨论了在均匀光波的最佳校正状态下,高斯光束初级象差同α的关系,得到高斯光束的初级象差可按照均匀光波象差理论进行校正的结论. 相似文献
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《中国光学快报(英文版)》2016,(4)
This Letter presents an optical design method based on the Seidel aberration theory for dynamic refocus systems.The function of a dynamic refocus system is to increase the amount of return photons when a pulsed laser travels over an extended height range. In this study, the dynamic refocus system is a short focal image system. The aberrations of the dynamic refocus system are calculated individually. Aplanatic lenses are used to eliminate the main spherical aberration. A field lens is used to change the stop position in order to eliminate comas and astigmatism. The effectiveness of the initial design results are confirmed, and the designed dynamic refocus objective with an aperture of F-number 0.98 and a focal length of 14.325 mm is achieved. The total motion of the dynamic refocus mirror is approximately 216 at heights that ranged from 8 to 18 km. The optimum result shows that the dynamic refocus system is an ideal optical image system at each conjugating height with10 km sample thicknesses. 相似文献
16.
为探究二次曲面前房型有晶体眼人工晶体的球差矫正特性,进行了球面和二次曲面有晶体眼人工晶体的设计,并利用像差理论对二者的球差矫正特性进行了研究.基于R.Navarro等人提出的模型眼得到屈光不正眼模型,利用ZEMAX光学软件分别设计了可矫正屈光不正人眼的球面与二次曲面前房型有晶体眼人工晶体.通过对光学传递函数和Zernike球差系数的比较,以及对Seidel球差分布系数的计算分析发现:在保证屈光不正矫正至正常水平的前提下,较之传统球面人工晶体,二次曲面的引入仅对远视眼的球差有矫正作用,并使光学传递函数显著改善|而对近视眼而言,二次曲面人工晶体的球差矫正效果与球面人工晶体相当.这一结论对前房型有晶体眼人工晶体的设计和应用具有重要的理论指导意义. 相似文献
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折射率失配对双光子三维光存储中像差的影响 总被引:5,自引:3,他引:2
双光子吸收三维光信息存储是实现高密度光存储的重要方法。三维数据写入过程中光束需经过两层不同的介质(如空气和存储材料),对像差和存储效果产生很大的影响,因此在理论和实验上分析系统各项光学参量对折射率失配引起的像差和存储效果的影响具有很大的意义。首先建立光学存储系统模型,在平行平板条件下,利用波像差函数推导展开,获得五项初级(赛德耳)像差,即球差、彗差、像散、场曲、畸变,然后对于存储材料在水平和倾斜两种情况下对初级像差进行模拟计算与分析,理论模拟与实验表明:物镜的数值孔径越大,像差随着存储深度增加而增大的速度就越快。 相似文献
18.
A novel design of a diode-side-pumped bounce amplifier laser is described that can produce a high-power TEM00 mode and Laguerre–Gaussian (LG) vortex mode operation with high circularity and low astigmatism. The design utilises control
of pump size and bounce angle such that the laser mode experiences substantially circular symmetric gain and spherical thermal
lensing, in a highly compact fundamental mode resonator. In a simple plane–plane Nd:YVO4 laser resonator with no other optical components and total length of just 13.4 cm, highly circularised TEM00 operation is produced at wavelength 1064 nm, with 14.2 W of power and high beam quality M
2<1.05. Stable Q-switched TEM00 operation is demonstrated up to 900 kHz and second harmonic power of 7.2 W at 532 nm is generated with conversion efficiency
up to 64%. Minor modification of the design to exploit the spherical aberration of the thermal lens is shown to allow for
generation of a doughnut-shaped LG vortex mode with average power 16.6 W, maintaining extremely low astigmatism. Q-switched
operation of the vortex mode is accomplished up to 400 kHz. A detailed numerical thermal analysis of the amplifier design
is performed and gives quantitative agreement with experimental results. 相似文献
19.
S. Bonora 《Optics Communications》2011,284(13):3467-3473
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采用量子模型对近共振激光驻波原子透镜会聚Cr原子束、形成纳米量级光栅结构的物理过程进行数值模拟。为提高原子透镜的成像质量,对各种像差,如衍射像差、球差、色差、及原子束发散角、原子磁支能级、原子同位素等因素引起的像差进行了理论分析。模拟结果表明,相比粒子光学模型,量子模型能更加精确地描述原子会聚结果,且能解释原子在驻波光场中的衍射现象。在各种像差中,原子束发散角是最主要的因素,其影响大于衍射像差、球差、色差。原子的磁支能级、同位素等因素对像差影响很小,可以忽略不计。激光冷却准直原子束的方法可以减小束发散角引起的像差,压缩原子速度Vz分布范围的方法可以减小色差。 相似文献