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compact disc reading click to hear : compact disc reading

During playback of a compact disc, a sensor analyzes laser beam variations reflected by the disc’s surface to re-create the original sound signal.
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aluminum layer laser beam resin surface objective lens asperity

aluminum layer click to hear : aluminum layer

The surface of the disc is covered with a thin layer of aluminum, which reflects the laser beam toward the sensor.

laser beam click to hear : laser beam

Highly concentrated light beam that scans the surface of a disc; the pits and asperities determine how the light beam is reflected.

resin surface click to hear : resin surface

Transparent film that covers and protects the aluminum layer.

objective lens click to hear : objective lens

Optical system made up of a set of lenses attached to a mount; it focuses the laser beam onto the section to be played.

asperity click to hear : asperity

Each of the small protuberances of varying length that encode data on the disc’s surface.