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compact disc readingclick to hear

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.
compact disc reading aluminum layer laser beam resin surface objective lens asperity

aluminum layer click to hear

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

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

Transparent film that covers and protects the aluminum layer.

objective lens click to hear

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

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