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- The compact disc provides an excellent example of the application of basic physics principles, from the derivation of the signal by interference to the dependence of audio frequency response and playing time on the optical wavelength used.
ui.adsabs.harvard.edu/abs/1993PhyEd..28...15C/abstract
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The physics of the compact disc. John A Cope. The compact disc provides an excellent example of the appllcatlon of bask physlcs prlndples, from the derlvatlon of the signal by Intetference to the dependence of audio frequency response and playing time on the optical wavelength used.
The compact disc provides an excellent example of the application of basic physics principles, from the derivation of the signal by interference to the dependence of audio frequency response and playing time on the optical wavelength used.
Jan 1, 1993 · The compact disc provides an excellent example of the application of basic physics principles, from the derivation of the signal by interference to the dependence of audio frequency response and playing time on the optical wavelength used.
- John A Cope
- 1993
- Overview
- Physical characteristics
- Recording and replication
- Playback
compact disc (CD), a molded plastic disc containing digital data that is scanned by a laser beam for the reproduction of recorded sound and other information. Since its commercial introduction in 1982, the audio CD has almost completely replaced the phonograph disc (or record) for high-fidelity recorded music. Coinvented by Philips Electronics NV a...
A standard CD is 120 mm (4.75 inch) in diameter and 1.2 mm (0.05 inch) thick. It is composed of a clear polycarbonate plastic substrate, a reflective metallic layer, and a clear protective coating of acrylic plastic. The reflective metallic layer is where audio data is read in the form of minuscule (as short as 0.83 micrometre) depressions (pits) a...
The production of a CD begins with a digital tape master supplied by the recording studio (see also digital sound recording). The information on this tape is used to modulate a beam of light from a blue laser as it traces a spiral path on the surface of a spinning glass disc. The glass is coated with a photosensitive material that dissolves where it is exposed to laser pulses, forming the pits. This “glass master” is coated with a thin layer of nickel to form a “metal master,” and the metal master in turn is used to produce a number of “mothers.” Each mother serves as the master for several metal “stampers,” onto which molten polycarbonate is injected for molding into clear plastic discs. Each disc is exposed to a stream of vaporized or atomized aluminum, which forms the reflective layer, and is then coated with the protective acrylic layer. The entire production process is carried out under conditions of laboratory-like cleanliness and control.
By the mid-1990s, however, developments in computer technology advanced such that CD recording and replication could avoid the need for a digital tape master. High-quality sound recordings could be sent from the microphone or other device directly to computer programs whose digital files could be stored on the computer’s hard disk (or magnetic storage media) before being transferred to a CD.
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Electronics & Gadgets Quiz
When a disc is inserted into a CD player, the disc’s track is scanned by a low-intensity infrared laser with a 1-micrometre-diameter focal point. In order for the laser to maintain a constant scanning rate, the disc’s rotation rate decreases from 500 to 200 revolutions per minute as the light beam spirals out from the disc’s centre. (Some CD player...
- The Editors of Encyclopaedia Britannica
Oct 15, 1992 · The text of this new edition has been thoroughly overhauled to take note of all these developments; in addition there is more information on the laboratory origins of the compact disc and the principles underlying the format.
A compact disc (CD), or optical disc, is a thin, circular wafer of clear plastic and metal measuring 4.75 inches (120 centimeters) in diameter with a small hole in its center. CDs store different kinds of data or information: sound, text, or pictures (both still and moving).
Apr 17, 2018 · Nature Electronics - An international collaboration between Philips and the Sony Corporation led to the creation of the compact disc. Kees A. Schouhamer Immink explains how it came about.
