HD DVD光盘格式的发展与信号处理技术

1、引言在光盘存储技术中,减小激光波长并提高物镜的数值孔径(NA:Numerical Aperture),可以有效的缩小聚焦光斑的尺寸,从而提高信息记录密度。HD DVD采用了405nm的激光波长和0.65的数值孔径,以及数值孔径为0.65的聚焦物镜,因此其记录密度显著高于传统的DVD。对于单面单层的HD DVD光盘而言,只读型HD DVD-ROM与可录型HD DVD-R的盘片容量为15GB,而可擦写型HD2DVD-RAM的盘片容量为20GB。与当前使用的DVD(单面单层盘片容量4.7GB)相比,HD DVD的容量增长达到3倍以上。另一方面,随着激光波长的减小和物镜NA值的提高,由光盘和…     

柔性光盘系统技术原理与发展概述

随着高清电视节目的日益普及,大容量光盘系统的市场需求也在日益增加。目前,提高光盘容量的主要方法是通过采用短波长的蓝色激光和大数值孔径的物镜来减小读写光斑的尺寸。BD(Blu-ray disc)光盘正是采用了波长为405nm的蓝紫激光器和数值孔径(NA:Numerical Aperture)为0.85的物镜,从而将单面单层光盘的存储容量从4.7GB提高到25GB。     

蓝光光盘(Blu-ray Disc＆HD-DVD)技术的发展

随着时代的演进、信息的发展及多媒体的普及,记录媒体需具备更高的记录密度及容量才符合信息存储的需求。由于传统光盘的记录密度受限于读出光斑大小,即光学的衍射极限(diffraction limit)0.61λ/NA(λ:激光波长,NA:物镜的数值孔径(Numerical Aperture,NA))的限制,所以传统光盘技术要提高记录密度,一般可使用短波长激光或提高物镜的数值孔径使光斑大小缩小,例如CD(78 nm,NA:0.45)提升至DVD(650 nm,NA:0.6)到蓝光光盘(405 nm,NA:0.85),如图一所示。     

多阶光存储技术原理

1.引言为了提高光存储系统的容量和数据传输率,在现有光盘系统的基础上,人们提出并研究了多种解决方案,其中为人所熟知的就是减小激光的波长和增大物镜的数值孔径。另外一种也很有发展前景的方案就是采用多阶技术。与传统光存储系统中采用的二阶编码技术相比,多阶技术可以显著地提高存储线密度;同时可并行地提高读写速度。目前存在着多种多阶技术,包括Sony公司的SCIPER(Single CarrierIndependent Pit Edge Recording)技术和GBR(Groove BasebandRecording)技术、Philips公司的LML(Limited Multi-Level)技术、Sharp公司的PEDM(Pit Edge and Depth     

采用推挽信号的径向翘曲检测方法

1.前言高密度光盘系统采用高数值孔径(NA:aNumerical Aperture)的物镜和短波长(λ)的激光光源,由物镜和光盘之间相对的径向翘曲引起的光斑彗差与NA3/λ成正比增长。光斑的彗差会大大降低光盘系统的读写性能,所以,通过检测并补偿盘片的径向翘曲(RadialaTilt),可以提高光盘系统的可靠性。目前已有多种不同的径向翘曲检测方法得以实际应用,但是尚未考虑在已记录轨道和未记录轨道的边界区域(以下称为记录边界)的情况。本文提出了一种采用推挽(Push-Pull)信号来检测径向翘曲的新方法,即使对盘片上记录边界位置的径向翘曲都能进行高精度的检测…     

405nm蓝光半导体激光器的多阶读写控制

近年来,对于光存储容量的需求越来越大,许多新 的技术也随之涌现。进一步减小激光器波长,采用大数 值孔径透镜是行之有效的方案,很容易在下一代光存储 行业中得以应用。而多阶存储技术的应用可以进一步 增大光存储容量和数据传输率。目前,提出并设计了一 种多阶蓝光存储系统,使用405nm半导体激光器和数值 孔径为0．95的物镜。其中使用GaN材料制作的波长 405nm的蓝光半导体激光器,目前仅有日亚等极少数公 司能够生产,但并不提供驱动芯片。因此,自行设计多 阶读写驱动电路,是完成多阶蓝光存储系统的关键。     

BD蓝光光盘的复制方法及关键技术

光盘(Optical disc)从CD到DVD,直到现在发展到蓝光光盘(在本文中,将以Blu-ray Disc为例),都是为了在同样尺寸的光盘上存储或记录更大容量的信息。其中最有效的方法是缩短记录／读取的激光的波长和增大记录／读取光学头系统物镜的数值孔径(NA)。从     

多阶光存储技术研究进展

一、前言 信息技术的发展对光存储系统容量和数据传输率提 出了越来越高的要求。传统光存储受到光学衍射极限的 限制,采用缩短激光波长和增大数值孔径的方法来提高 存储密度的空间非常有限。多阶光存储技术能够在不改 变光学数值孔径的情况下,利用先进的信号处理与编码 技术,显著提高存储容量和数据传输率,目前已经成为 国内外光存储研究的热点方向之一。     

新一代高密度存储技术—蓝光DVD

在全球的光存储市场,DVD-ROM驱动器在价格上逼近CD-ROM驱动器,可擦写的DVD-RW和DVD+RW驱动器产品也在纷纷上市,未来的光存储将是密度更高、读写速度更快的DVD技术的天下。当前的DVD技术虽然是CD技术的超越,不过由于它们都采用红色激光波段进行数据的读取和刻写,使得这种超越的步伐还算不上太大。初露端倪的新一代蓝光DVD技术采用全新的蓝色激光波段进行工作,存储容量再次翻越近6倍之多,使高密度光存储的技术突破步伐迈得更大。     

用于双物镜的旋转力矩器设计

随着光存储技术的不断发展,下一代高密度光盘存储系统都采用了波长为405nm的蓝紫色半导体光管,以及具有更高数值孔径(Numerical Aperture,缩写为NA,后同)的物镜。不过,不论是HD DVD也好,还是Blu-ray Disc(缩写为BD,后同)也罢,都面临着和现有普通的DVD/CD系统的兼容性要求。由于在一个系统中采用两个光学头来实现这种兼容性要求的作法,在IT产品未来的竞争中会带来诸多局限性,是一种不合算的技术方案,所以现在越来越多的人们开始想到设计一种可以满足三种不同光盘格式兼容性要求的单光学头的方案。考虑到在BD/DVD/CD兼容光学头的设…     

Design of an integrated optical pickup with NA of 0.85 for small form factor optical disk drives

We design an integrated optical pickup for small form factor optical disk drives. The specifications of the pickup are compatible with those of the Blu-ray disk (BD) in terms of numerical aperture (NA) of the objective lens, the wavelength of the laser diode, and the thickness of the cover layer. The objective lens unit with NA of 0.85 consists of two aspherical refractive lenses and a diffractive optical element for compensation of the chromatic aberration. Each element of objective lens unit will be fabricated on a wafer as an array type, and the three wafers will be aligned and bonded to form an objective lens array. Therefore, elements of the objective lens unit are designed to have sufficient alignment tolerances for various directions such as de-center and tilt. The optical performances of the objective lens unit are evaluated by simulation against various disturbances such as wavelength change of emitting light from laser diode, misalignments, etc. We also design a quarter wave plate, a polarized holographic optical element, and the shape of photodiode integrated circuit array to generate focusing and tracking error signals. The entire height of the pickup including working distance is 2 mm, and the effective pupil diameter of the objective lens unit is less than 1 mm.     

Design of optical path of pickup for small form factor optical disk drive

We designed an optical path of pickup for the small form factor optical disk drive that is compatible with Blu-ray Disc format using 405 nm wavelength laser, 0.85 NA objective lens, and the 0.1-mm thick cover layer. The optical path consists of a high NA objective lens, a micro compensatory lens that is fabricated by micro-molding process, three reflective mirrors and a partial mirror. The optical performance of the optical path is analyzed and the expected yield ratio is calculated for 22 tolerance parameters by using Monte Carlo method. Finally, the micro compensatory lens is fabricated by micro-molding process.     

Design of wafer-based NA 0.85 micro objective lens and integrated pick up module for small sized optical drive

In this paper, we propose the design of a wafer-based micro objective lens with numerical aperture (NA) 0.85 using a 405 nm blue-violet laser. The total length of the lens is 1.36 mm. The micro objective lens consists of three layers that are a hologram optical element for reducing the aberration and two grinded and polished ball for making optical power to achieve NA 0.85. The lens could be applied to an integrated optical pickup module. The approximate size of the optical pickup module is 3 mm[W] × 3 mm[D] × 3 mm[H] including the wafer-based objective lens, which is suitable for realizing a small sized optical drive based on Blu-ray Disc. The wafer-based design could offer precise alignment, easy handling and high mass productivity with micro electro mechanical system technology.     

Thickness tolerance compensation of SIL first surface near-field recording with replicated lens on SIL

In this paper, we propose a novel optics design for improving the thickness tolerance of a super-hemispherical solid immersion lens (SIL) that is usually used in near-field recording for high data density. To obtain the improved thickness tolerance of a SIL and a high numerical aperture simultaneously, an aspheric replicated lens is added on the SIL. Using an additional aspheric replicated lens, spherical aberration which induces the tight thickness tolerance of the SIL is effectively reduced, therefore it was able to improve the thickness tolerance of the SIL, maintaining high NA equal to that of super-hemispherical SIL. In addition, in this paper, other various tolerances such as decenter and tilt are considered to make sure of the possibility of fabrication.     

Development of dynamic tilt control method and servo algorithm in gap servo NFR

In the NFR system, since the gap between SIL and disc is under 100 nm, the traditional servo method can not be applied, and its modification is necessary for the stable servo performance. The gap error servo method is well-known as a typical servo in the NFR system (Verschuren et al. in JJAP 44:3554–3558, 2005) for focusing direction, and pull-in procedure (Zijp et al. in IEEE Trans Magn 41(2):1042–1046, 2005) and hand-over (Lee et al. in JJAP 44(5B):3423–3426, 2005) methods are also good approaches for the stable servo in the near field. We can obtain a good servo performance using the gap error servo method, and its experimental result shows that it is consistent with the previous researches. In case of the track servo, 1-beam push pull was generally used for the traditional ODD. However, it contains a DC offset components with lens movement, and thus, we can not have a good RF signal and track error signal simultaneously. Therefore, in this paper we introduce the modified servo method, which uses gap error lens position and the successful servo result for surface disc and 1.7 μm cover layer disc. Test was performed with a 4-axis actuator, and it gives a good performance not only for gap and track servo, but also for radial and tangential tilt. Finally, we suggested the decoupling method between track-shift and tilt components using the gap error differential signal and the simple slit structure. Based on the experimental result, it was verified that slit structure can eliminate the track-shift component effectively.     

Collision-free finishing toolpaths from visibility data

We present a series of algorithms and heuristics for generating collision-free 5-axis CNC finishing toolpaths automatically. These algorithms are based on the core concept of visibility, which can be generated in high resolution by discretizing the part and using graphics hardware as described in earlier papers by the authors. Using this visibility data for finish machining is a challenge, and we show how it can be used to generate globally collision-free 5-axis finishing toolpaths while also considering machine limits, tool tilt, cusp height limits, tool pitch limits and the need to keep toolpaths continuous. We then show how the toolpath can be verified during the path generation process, how collision-free interpolation can be carried out and how the sampling can be adjusted to ensure that the finishing toolpaths are accurate. We end with examples of 5-axis toolpaths generated for complex parts.     

High-performance optical pick-up actuator with singlet objective lens for BD/DVD/CD compatible drive

For perfect compatibility of BD/DVD/CD, a heavy objective lens assembly is inevitable. However, BD format needs very high transfer rate to edit the contents of HD media, without delay. And performance of an optical pick-up actuator is one of several keys to make it possible. To secure high sensitivity, we introduce a magnetic circuit composed of two 3-pole magnets. As a result of it, despite heavy weight of lens assembly, we achieved high performance enough to operate the disc drive as BD CLV 4X.     

激光干涉光刻工艺开发与应用研究

成功开发出以劳厄干涉为基础的激光干涉光刻系统与工艺,该工艺可在大面积范围内加工二维周期性图形,非常适合于生产光电子器件和微电子器件的周期性结构。通过实验研究了使用该工艺加工表面纳米结构的流程,对比了几种光刻胶在该工艺中的性能特点。该工艺不需要掩模、昂贵的短波长光源和成像透镜。初步实验结果表明:该工艺可以生产大面积亚微米周期的光栅、点阵以及锥形结构,为激光干涉光刻加工纳米结构的后续工作奠定了基础。     

Design of near-field recording optics using truncated hemispherical SIL with cover-layer incident dual recording layers

In this paper, we propose a novel optics design for media inside near-field recording (NFR) using a truncated hemispherical solid immersion lens (HMS). To obtain strong advantage of data protection and high data capacity simultaneously, a truncated HMS based near field optics with cover-layer incident dual recording layers is designed. In this design, to improve the small optical tolerance of the truncated HMS unit and to adjust dual focusing positions, an additional aspheric lens surface is added on top of the truncated HMS and it is combined with zoom optics composed of two single lenses having a low numerical aperture (NA). Also, to compensate for chromatic aberration, which is a serious problem for optics using a blue laser diode, a diffractive optical element is also designed. Using zoom optics, an additional aspheric lens surface, and a diffractive optical element together, the wavefront aberration and chromatic aberration are effectively reduced in a broad range of cover-layer thicknesses and wavelength variations. In addition, in this paper, the effect of a gap induced aberration is investigated by analyzing the different behavior of each TM and TE wave for the cover-layer incident NFR optics.Paper presented at the 15th Annual Symposium on Information Storage and Processing Systems, Santa Clara, CA, USA, 28–29 June, 2005.     

Bessel Gaussian Beam Propagation through Turbulence in Free Space Optical Communication

This paper investigated the experimental demonstration of jitter analysis for Bessel Gaussian beam propagation through the atmospheric turbulence conditions using two different wavelength lasers such as red and green laser. Axicon lens is used to generate Bessel Gaussian beam experimentally and different modulation schemes such as PAM, PPM, PWM, ASK, BPSK and QPSK are used to analyze the phase and time jitter. The Plano-Convex type Axicon is used to create a ring shaped approximation of a Bessel Gaussian beam which increases in diameter over distance while retaining a constant ring thickness. In this BG beam propagation, for red laser the noted phase jitter value is 45.196 radians in ASK and for green laser 36.955 radians in with turbulence conditions. Hence the lower wavelength BG laser beam (green laser) is more energetic than the lower wavelength BG laser beam (red laser).