光存储技术

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CD Construction
The compact disc comprises a sandwich as shown in the diagram. A 1.2 mm thick polycarbonate substrate containing pits moulded into the upper surface is coated with aluminium, which is then protected by a lacquer on which the disc label is printed.
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CD Physical Specification
The main Compact Disc parameters are given in the table below.
Parameter Diameter:
第五章 光存储技术
Value 12 (or 8) cm 1.2 mm 0.5 microns 0.8 to 3 microns 0.15 microns 1.3 m/s 1.6 microns 770 to 830 nm 76m 30s 99 max EFM 4.3218 Mb/s
Comments Few 8 cm CDs are made Tolerance +0.3, -0.1 mm Approximate Depends on data stored Approximate Tolerance +/- 0.1 m/s Tolerance +/- 0.1 microns Typically 780 nm Playing times can be longer Can use indexes to subdivide tracks 8 to 14 bits + 3 merge bits Actual raw data rate 回到第一页
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CD Layout
The layout of the CD is shown in the diagram
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CDs measure 12cm in diameter with a 15mm diameter centre hole. The audio or computer data is stored from radius 25mm (after the leadlead-in) to radius 58mm maximum where the leadlead-out starts.
第五章 光存储技术
第五章 光存储技术
内容提要
本章主要介绍光存储系统的相关技术。包括光盘的 分类、标准，光盘读写的原理，光盘的格式等。
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内容提纲
第五章 光存储技术
5.1 光存储技术概述 5.2 只读光盘存储器 5.3 光盘存储器格式 5.4 CD的编码方法简介 CD的编码方法简介
Channel bit rate:
Compact Discs are normally 12 cm in diameter and 1.2 mm thick. The pits containing the audio or other data are about 0.15 microns deep and their length varies from 0.8 microns minimum (3 units in length) to 3 microns maximum (11 units in length) depending on the data stored as shown in the diagram below. Pits (and the lands between them) can therefore have 9 values for length, the signals read from the pits being referred to as I3 to I11. The modulation used ensures that these values are maintained.
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Laser Technology
CDs rely on laser technology to read (and write) the data on discs. The word LASER stands for Light Amplification by Stimulated Emission of Radiation. Lasers Radiation. generate coherent light, which allows the light beam to be focused to a very small spot size, the spot diameter being equal to the wavelength divided by the numerical aperture. The advent of lasers and in particular low cost laser emitting diodes has allowed the compact disc technology to become one of 回到第一页 the most successful consumer electronic
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§5 . 2
只读光盘存储器
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首先简要回顾一以下20年来CD发展的历史，然后 首先简要回顾一以下20年来CD发展的历史，然后 对CD的工作原理进行一个简要的描述，最后介绍 CD的工作原理进行一个简要的描述，最后介绍 CD 与 DVD 的相关技术与应用。
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The part of the disc containing data is divided into three areas:
LeadLead-in (from radius 23 mm to 25 mm) which contains digital silence in the main channel plus the Table of Contents in the subcode Q-channel. It Qalso allows the laser pickup head to follow the pits and synchronise to the audio or computer data before the start of the program area. The length of the lead-in is determined by the need to store the leadTable of Contents for up to 99 tracks. Program area (from radius 25mm to 58 mm maximum) which contains up to about 80 minutes of data divided into 99 tracks maximum. LeadLead-out which contains digital silence or zero 回到第一页 data. This defines the end of the CD program area.
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Laser Disc
In the late 60s, Philips developed the laser video disc, the first such application of the laser for a consumer electronics product. The 30cm disc was capable of storing up to 60mins of analogue video per side. A low power laser was used to read the video information stored in pits in the disc surface. The video and audio signals are represented in analogue form by these pits which were arranged in a spiral pattern, like vinyl records.
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Essential Technologies
Pulse Code Modulation (PCM), invented in 1937 by Alec Reeves who was working in for STL in London at the time. He received a CBE in 1969 for his work on PCM. ReedReed-Solomon error correction codes, codes, which were invented by Reed and Solomon in 1960, but were based on earlier work by Hamming in 1950. for more information. The Laser, which was invented at the Bell Laser, Labs in 1958.
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Hale Waihona Puke Baidu
Compact Disc
CD players use light emitting diode lasers, which are compact and low cost, to read the data contained in pits in the surface of the disc.
Thickness: Width of pits: Length of pits: Depth of pits: Scan velocity: Track pitch: Laser wavelength: Playing time: Number of tracks: Modulation
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§5 . 1
光存储技术概述
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The compact disc celebrated 20 years since its launch in October 1982. The optical disc format has been very successful in this time and provides a compact and reliable distribution format not just for music but for other applications as well. Even with the introduction of DVD, the CD is still forecast to remain the mainstream format for music for some years to come. "Any computer data can be pre-recorded on a CD-ROM" preCDCITED FROM: http://www.disctronics.co.uk/