Video disk signal

In a similar way, the video disk reconverts the signal produced by the Kerr effect on a thin film of an amorphous substance such as Tb-Fe sputtered on a substrate disk made of plastic or glass. The Tb-Fe film functions like a perpendicular magneto-optical memory... 

Not in the class of digital recording storage media are video CDs with diameters of 200 and 300 mm, respectively. These are storage disks for recording the analogue signal of videos and are of air-sandwich constmction with two poly(methyl methacrylate) disks. 

One of the most popular systems is a laser disk for audio known as a compact disk (CD), in which PCM signals are recorded on the rear side of a plastic transparent disk and laser light reads them as shown in Fig. 20. A digital video... 

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