computer

Saturday, February 5, 2011

optical storage device

                                                                                   Optical Storage Device    
Optical  storage devices  are devices that use laser light technology to retrieve and store data.
CD-ROM drives,CD-RW drives,Combo drives and DVD RW drives are the most popular optical storage devices.An optical disk is used in the optical storage drive.an optical disc is a circular disk made up of rigid  plastic and is coated with a thin metal or other highly reflecting material.while writing data,high intensity laser beam is focused on the metal coated surface of the optical disk and it forms tiny holes(or pits)on the metal coated surface of the disk along its tracks.a pit represent a value of 1 and  a flat spot or land represents a value of 0.while reading,low intensity laser beam is focused on the disk surface and the reflected laser is sensed by photodiode.the intensity of reflected laser beam from the pits is weak and is high from the flat spots.these high and low patterns of the reflected laser beam are sense by photodiode and are converted into electronic signals. the most commonly used optical disks are CD-ROM,CD-RW andDVD-ROM.

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