Labels:text | screenshot | font | diagram | number | map OCR: CD-ROM DRIVE SIMPLIFIED OPTICAL PATH Loquer topcoat Aluminum -: Disc mirror layer Plastic Focus lens (1.2mm thick) 1/4 wave Laser beam polarizer plate Polarizing beam splitter Collimator lens Photo diode pick-up Laser diode sensor FIGURE 1: A CD drive uses a split laser beam to read digital information from a long spiral track of information carried on the CD. As one servo spins the CD, a tracking servo moves the head along the disc's radius, and a focus servo moves the lens to keep the beam properly focused on the series of "pits" that contain the data track's binary information.
