Objective Lens System for Variable Thickness of Disk Base

As the thickness of a disk base is varied, the variation of spherical aberration becomes remarkable. An objective lens system with compensating lenses on the light source side is designed. By moving the compensating lenses along the optical axis backward or forward, the spherical aberration caused by the variation in thickness of the disk base is corrected.     

Feasibility analysis of solid immersion lens-based dual-layer near-field recording optics with a numerical aperture of 1.84

A dual-layer near-field recording (NFR) optical system with a high numerical aperture (NA) of 1.84 was designed by appropriate cover and spacing layer selection, using layers with refractive indices of 2.0. The designed aplanatic imaging optics exhibited additional aberrations in the multi-layered stack, mainly due to the air-gap and spacer layer. Given optics designed only to compensate for aberrations caused by a 2-μm-thick cover-layer, a 3-μm-thick spacer layer induces 96.2 mλ_rms and 6.5 mλ_rms of spherical aberration and defocus, respectively. A complete electric field calculation analysis for the inside of the multi-layer stack verified that diffraction-limited spot quality can be ensured on the recording layer with phase-only correction. As the aberration caused by the multi-layered stack cannot be corrected perfectly, due to the high oscillation of the aberration function along the radial direction in the exit pupil, three different types of liquid crystal (LC) electrodes were considered for practical implementation. Of the three phase-correction methods, the approximate linear phase-correction method was the most tolerant of axis decenter from the optical axis, providing acceptable diffraction-limited correction performance.     

Optical Super-Resolution Pickup Using a Liquid Crystal Shutter for CAD-MSR Magnetooptical Disk

We demonstrated characteristics of an optical super-resolution pickup using a liquid crystal (LC) shutter as a shading plate. The problem of laser power loss was solved by an LC shutter which was turned off for writing and turned on for reading. Combining this with CAD-MSR disk, we obtained good signals of high-density recording. This combination increases efficiency of laser power and does not require a slit to eliminate side-lobes. The laser power efficiency for writing is as high as 34% and linear bit density reaches 0.255 μm/bit even with a wavelength of 680 nm and an objective lens NA of 0.60.     

Characterization of aplanatic hologram lenses for optical disk pick-ups

Imaging characteristics for holographic objective lenses application to optical disk pick-ups was analyzed by a comparison between flat and spherical aplanatic hologram lenses with the aid of the third order aberration theory and ray tracing method. The aplanatic hologram lens image field was 0.5 deg for NA=0.5 with focal length f=5 mm under the Marechal criterion. The results indicates that the aplanatic hologram lenses are feasible for optical disk applications.     

Film-thickness Error Analysis of Optical Disk Systems

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｒｅｃｅｎｔｌｙｏｐｔｉｃａｌｄｉｓｋｓａｂｌｅｔｏｓｔｏｒｅａｌａｒｇｅｑｕａｎｔｉｔｙｏｆｉｎｆｏｒｍａｔｉｏｎｈａｖｅｂｅｅｎｕｓｅｄａｓｃｏｍｐａｃｔｄｉｓｋ (ＣＤ ) ,ｄｉｇｉｔａｌｖｅｒｓａｔｉｌｅｄｉｓｋ(ＤＶＤ) ,ａｎｄｔｈｅｉｒｒｅｃｏｒｄａｂｌｅｏｒｒｅｗｒｉｔａｂｌｅｔｙｐｅｓ(ｓｕｃｈａｓＣＤ Ｒ ,ＣＤ ＲＷ ,ＤＶＤ Ｒ ,ａｎｄＤＶＤ ＲＡＭ ) [1 ] .Ａｎｏｐｔｉｃａｌｄｉｓｋｉｓａｋｉｎｄｏｆｍｕｌｔｉｌａｙｅｒｓｙｓｔｅｍｄｅｐｏｓｉｔｅｄｏｎａ…     

Single Telephoto Lens for Focus Error Detection with Astigmatic Method

An astigmatic method for focus error detection has been integrated into a singlet. The first convex and the second concave surfaces compose a telephoto system with a telephoto ratio of about 0.4. The first surface of the lens is rotationally symmetrical asphere and the second surface is a toric shape whose aspherical profiles correct spherical aberration. We implemented our optical design using a molded glass process. Its performance was confirmed using the optical head of a magneto-optical disk system.     

Skew aberration: a form of polarization aberration

We define a new class of aberration, skew aberration, which is a component of polarization aberration. Skew aberration is an intrinsic rotation of polarization states due to the geometric transformation of local coordinates, independent of coatings and interface polarization. Skew aberration in a radially symmetric system has the form of a circular retardance tilt plus coma aberration. Skew aberration causes undesired polarization distribution in the exit pupil. We demonstrate statistics on skew aberration of 2383 optical systems described in Code V's U.S. patent library [Code V Version 10.3 (Synopsys, 2011), pp. 22-24]; the mean skew aberration is 0.89° and the standard deviation is 1.37°. The maximum skew aberration found is 17.45° and the minimum is -11.33°. U.S. patent 2,896,506, which has ±7.01° of skew aberration, is analyzed in detail. Skew aberration should be of concern in microlithography optics and other high NA and large field of view optical systems.     

Diffractive-Refractive Achromatic Lens for Optical Disk System by Glass Molding

An erasable optical disk system requires an objective lens having minimum chromatic aberration. We estimated the chromatic aberration of a conventional refractive singlet. At shorter wavelengths, the focus shift of an objective lens exceeds its depth of focus. A diffractive-refractive hybrid lens can compensate chromatic aberration perfectly. Diffraction efficiency, however, decreases with the degree of compensation. We simulated the relationship between chromatic aberration and diffraction efficiency. Fabrication of designed lenses by glass molding was achieved, and the results showed excellent agreement with the simulation.     

A Differential Phase Detection Method for Tracking-Error Signals Using a Monolithic Confocal Laser Coupler

We previously presented the differential phase detection method using a monolithic confocal laser coupler with a confocal knife edge structure (the CKE device), which we call the CKE Pit-Edge method and which is applied to an optical disk system in which the disk has a pit depth of λ/4n. In this paper, the experimental results using this new method are reported. The experimental results agree well with the calculated results. Thus, tracking-error signals, which are very stable in the face of radial lens displacement, can be obtained for an optical disk with any pit depth using the CKE Push-Pull method and the CKE Pit-Edge method.     

光学合成孔径成像系统子孔径像差研究

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。     

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.     

Blue laser phase change recording system

The migration paths from DVD phase change recording with red laser to the next generation optical disk formats with blue laser and high NA optics are discussed with respect to optical aberration margins and disc capacities. A test system for the evaluation of phase change disks with more than 20 GB capacity is presented and first results of the recording performance are shown.     

Aberration Functions for Microlithographic Optics

In this paper a newly proposed polynomial series for aberration expression is reviewed. The new series can be utilized to express aberration distribution of a high NA and wide field optical system like a microlithographic projection lens. Moreover, the new aberration functions can be used for the microlithographic lens manufacturing process because they can express each aberration component of a rotationally symmetric system with a small amount of decentering error and astigmatic (toric) error.     

Extending the depth of focus with high NA lens axicon

Based on vectorial Debye theory, tight focusing of x-polarized beam with high NA lens axicon is studied. The high NA lens axicon utilizes spherical aberration to duplicate the performance of an axicon and to create an extended focal line. The intensity distribution in the focal region is illustrated by numerical calculations. We show that the high NA lens axicon system can generates a sub wavelength beam (0.826λ) with depth of focus around 10λ.     

NA1.35投影光刻光学系统偏振像差的优化

为了实现NA1.35投影光刻光学系统高质量成像，在设计过程中除了控制波像差，还需进一步优化光学系统的偏振像差。利用Jones光瞳和物理光瞳表达了NA1.35投影光刻光学系统的偏振像差，并用二向衰减量与延迟量分析了光学系统偏振像差的大小；根据光线入射到不同光学面上最大入射角度的不同，为每个光学面设计相应的膜系以优化光学系统的偏振像差。相比于采用常规膜系，膜系优化后NA1.35投影光刻光学系统的二向衰减量和延迟量分别减小到了0.021 8、0.057 2 rad，即减小了光学系统的偏振像差。利用Prolith光刻仿真软件，分别对采用常规膜系和优化膜系的NA1.35投影光刻光学系统进行曝光性能仿真，结果显示:膜系优化后光学系统的成像对比度提高了4.4%，证明了NA1.35投影光刻光学系统偏振像差优化方法的有效性。     

Aberrations of a slightly inclined Gaussian beam in a symmetric optical system

We discuss the Seidel-type aberrations which degrade the quality of the Gaussian beam, while the beam axis is slightly inclined to the axis of an optical system. First we examine the evolution of a complex-source-point spherical wave through multiple spherical boundaries. Then we find a ray-optical solution for the diffracted beam that can be represented as a function of Seidel-type aberrations. We also formulate the characteristic parameters of the aberrated beam. If the beam axis is placed at the yz plane, the x component of beam quality factor is degraded by both spherical aberration and field curvature, and the difference in the x and y components of beam quality factor is caused by linear coma, linear astigmatism, and distortion. The fourth order theory of propagation of the Gaussian beam presented here may be applied to determine the parameters of a slightly inclined Gaussian in a symmetric optical system.     

极化子效应对量子盘中线性和非线性光吸收系数的影响

利用密度矩阵的方法,得出了考虑极化子效应的量子盘的线性和非线性光吸收系数的解析表达式,并以GaAs为例讨论了光吸收系数与不同的入射光子能量和量子盘的厚度之间的关系.结果表明,极化子效应对吸收系数有相当的影响 关键词： 量子盘 光学吸收系数 极化子效应     

Aberration-free optical refocusing in high numerical aperture microscopy

We describe a method of optical refocusing for high numerical aperture (NA) systems that is particularly relevant for confocal and multiphoton microscopy. This method avoids the spherical aberration that is common to other optical refocusing systems. We show that aberration-free images can be obtained over an axial scan range of 70 mum for a 1.4 NA objective lens. As refocusing is implemented remotely from the specimen, this method will enable high axial scan speeds without mechanical interference between the objective lens and the specimen.     

光盘光学系统的矢量衍射理论分析

本文以完整的矢量衍射理论分析了光盘光学系统。首先将入射的聚焦光束分解为平面波谱 ,得到每个平面波的振幅矢量 ;然后计算光盘对每个平面波的衍射 ,得到衍射波的振幅矢量 ,从而得到了整个衍射波场的空间频谱 ;最后计算物镜光瞳上的能通量 ,得到光盘系统的读出信号。在衍射计算中 ,光盘被定义为二维金属光栅 ,根据信息符的不同模型 ,选用坐标变换方法、耦合波方法或模态方法。对于典型的 DVD光学系统来说 ,矢量理论的结论与标量理论相差甚远 ,要得到正确的结果就必须采用矢量衍射理论     

面对称光学系统的初级波像差理论研究

非旋转轴对称光学系统波像差理论的建立有利于理解旋转 轴对称光学系统的装调误差和离轴三反射光学系统等非旋转轴对称光学系统的选型设计. 本文利用旋转轴对称球面光学系统的全口径初级波像差理论推导了子孔径面对称光学系统的初级波像差分布公式, 证明了面对称光学系统中的节点像差理论, 即除球差外的所有初级像差的零值节点偏离视场中心, 而不再是视场的旋转对称函数; 并首次阐述了多零值节点初级非对称像差产生的根源和变化特性. 该理论可以有效指导非对称光学系统初始结构的选择和优化设计过程. 关键词： 面对称 像差 几何光学