Optical disc

The technology of laser recording of information on optical discs was born long before the birth of personal computers and was developed more likely for special music players or for additional television devices. According to one of the sources, the priority in the development of "laser" technology belongs to Soviet scientists Alexander Prokhorov and Nikolai Basov - the creators of those same "cold" lasers that became the basis of various information reading devices not only in computers, but also in many other types of household appliances (in 1964, both scientists were awarded the Nobel Prize ). After only four years, Philips has already obtained the first patent for a method of reproducing data using a laser beam ^[1] .

However, at the World Electrotechnical Congress in 1977, Vyacheslav Petrov , a scientist in the field of optoelectronic materials science, information technology and optical information recording, an academician of the Ukrainian Academy of Sciences, proposed for the first time in the world, five years before the first compact discs , the concept of an optical disc as “a single The data carrier ", where justified principles of opto-mechanical storage devices ^[2] , is also a major designer of the first drive information ES5150 computer with removable optical disk capacity of 2500 MB and a fundamentally new world's first compact drive with an immersion optical recording cylinders ES5153 capacity of 200 MB for use in personal computers.

The idea of ​​using optical devices for recording and reproducing information, as they say, was in the air. The first, according to another source, was invented in 1958 by the American electrical engineer David Gregg , who patented it in 1961 ^[3] and, with improvements, in 1969 ^[4] . According to him, the idea to use the beam to obtain a picture came to him when he saw a photograph in the store, obtained using the latest electron microscope ^[3] . The method of recording and playback described in the Gregg patent is, in fact, the earliest form of DVD discs, and was used in 1990 by Pioneer Corporation to develop its own patent for an optical disc ^[5] .

Another American inventor, James Russell , is considered the discoverer of a method of recording a digital signal on optical media, which was applied to a thin metal film by burning with a powerful halogen lamp . Russell filed a patent application in 1966, a patent was granted to him in 1970. After the trial, the largest manufacturers of optical discs, which began their mass production in the early 1980s, Sony and Philips , were forced to pay Russell for the corresponding licenses , and then the rights to a patent were purchased from him by the Canadian company Optical Recording Corporation ^{[6] [7] [8]} .

The disks obtained by the technologies of both Gregg and Russell were flexible and used a transparent (transparent) reading method, which had a lot of drawbacks. In 1969, in the Netherlands, a natural physicist from the Philips research lab, Peter Kramer, invented an optical video disc with a reflective reading method - with a substrate that reflected a focused laser beam. The patent application was collected in 1972, but the patent was granted only in 1991 ^[9] . Essentially, it was Cramer’s invention that became the standard for optical discs. In 1975, Philips and MCA began jointly developing an industrial design of an optical video disc. Three years later, the long-awaited sample was presented in Atlanta under the name "Laserdisc" . MCA took up the production of discs, while Philips took up the production of playing devices. However, in a highly competitive market, the product was too expensive and the commercially unsuccessful partnership was terminated.

In Japan and the United States, before the advent of DVD media , Pioneer remained the leader in the production of optical video discs. Having said goodbye to MCA, Philips organized a partnership with the Japanese company Sony , together with which in 1979 it began developing not an video, but an audio disc. The magnetic media existing at that time noticeably lacked the volume and reliability of storing audio recordings, potentially they were an order of magnitude inferior to media made using optical technologies. The result of the collaboration was the invention and industrial production of audio disks in the early 1980s, which became a kind of technical breakthrough in the field of information storage - the gradual development of this technology, with the transition from analog to digital encoding, soon replaced magnetic media completely.

In the development that has taken place, optical disk production technologies distinguish between the so-called generations or generations , the main sign of which is the amount of information available for storage on one disk, which has increased many times over from generation to generation. To increase the volume and improve other significant characteristics allowed new laser recording methods using increasingly thin materials.

Researchers from Australian University of RMIT and Wuhan Institute of Technology, China, have developed a radically new type of high-performance high-capacity optical discs. One new disk can store up to 10 TB (terabytes) of data and ensure the safety of this data for more than six hundred years. The performance of the new optical disk is four times the information capacity of existing technologies and 300 times the duration of information storage ^[10] .

First Generation of Optical Discs

• Laser disc
• CD
• Minidisc

Second Generation of Optical Discs

• DVD
• Digital Multilayer Disk
• Dataplay
• Fluorescent multilayer disc
• Gd-rom
• Universal media disc

Third Generation of Optical Discs

• Blu-ray Disc
• HD DVD
• Forward versatile disc
• Ultra Density Optical
• Professional Disc for DATA
• Versatile Multilayer Disc

Fourth Generation Optical Disc

• Holographic versatile disc
• SuperRens Disc ^[11]
• Optical Disc Archive Advisory Group ^[12]

An optical disc drive is an electromechanical device for reading and (in most modern models) recording, using a laser , information from optical discs in the form of a plastic disc with a hole in the center ( CD , DVD , etc.). Developed by Philips and Sony in the late 1970s, originally for reading CDs, for abstracting from the format and type of a disk, it is commonly called a generic name for a drive based on the principle of reading information from media. The optical drive itself can be in the form of a constituent part of more complex equipment (for example, a domestic DVD player ) or can be produced as an independent device with a standard connection interface ( PATA , SATA , USB ), for example, for installation in a computer.

The following types of drives are available:

• CD-ROM drive is the simplest type of cd drive designed to be read-only cd discs.
• CD-RW drive is the same as the previous one, but it can only write to CD-R / RW discs.
• DVD-ROM drive - its purpose is only to read DVDs.
• DVD / CD-RW drive - the same DVD-ROM , but capable of burning to CD-R / RW disks (combo drive).
• DVD-RW drive - a drive that can not only read DVDs, but also write to them.
• DVD-RW DL drive - unlike the previous type of DVD RW, it is also capable of recording on dual-layer optical DVD media, which differ from the usual ones with a larger capacity.
• Blu-ray drive ( BD-ROM ) is an advanced optical media technology based on the use of a laser with a wavelength of 405 nm of “blue” (actually purple) color.
• The BD-RE drive is capable of reading / writing to Blu-ray discs.
• The HD DVD drive is the next generation of optical discs designed primarily for storing high-definition movies (HDTV). The new media format allows you to record three times the amount of data compared to DVD. Single-layer HD DVDs have a capacity of 15 GB, double-layer - 30 GB. Typically, an HD DVD drive can read all DVD and CD formats.
• HD DVD-ROM drive - A drive that reads HD DVDs. The format was closed in February 2008.
• HD DVD / DVD-RW drive - unlike the previous one, it can burn to discs of such formats as DVD-R, DVD + R, DVD-RW, DVD + RW, CD-R, CD-RW.
• GD-ROM drive
• UMD drive.

Structurally, drives of all types of disks are quite similar. They contain:

• chassis (with a tray for loading, or a slot loader);
• spindle motor , is used to bring the disk into rotation with a constant or variable linear speed.
• The optical head system consists of the head itself and its movement system:
  • In the head assembly there is a laser emitter based on an infrared laser LED, a focusing system, a photodetector and a preamplifier. The focusing system is a movable lens, driven by a voice coil electromagnetic system (voice coil), made by analogy with a moving loudspeaker system - a change in the magnetic field causes the lens to move and focus the laser beam.
  • the head movement system has its own drive motor, which drives the carriage with the optical head using a gear or worm gear. To eliminate play, a connection with an initial voltage is used: with a worm gear - spring-loaded balls, with a gear - spring-loaded pairs of gears in different directions.
• an electronics board where all drive control circuits are located, an interface with a computer controller, interface connectors and an audio signal output.

• Optical disc file system software
• Optical disk image
• Emulator CD and DVD drives
• Packaged Volumetric Optical Disk
• Copy protection
• Recovery disk

• Reference Guide for Optical Media by Terence O'Kelly (Memorex Inc.)
• Taylor, J., Zink, M., Crawford, C. & Armbrust, C. Blu-ray Disc Demystified . McGraw-Hill Education, 2008