Essential Guide to Computer Data Storage: From Floppy to DVD, The

MO System: Basic Design

The MO drive's optical design is quite similar to that of the CD drive and DVD drive (see Figure 5-4) but, it is optimized for measuring slight changes in the light polarization upon reflecting from the disk. The differential detection system is the basis of the MO system's readout. A so-called “leaky” beam-splitter channels half of the reflected light away from the laser and toward the detectors. The polarizing beam-splitter splits the beam into two reflected components of the polarized beam: parallel and perpendicular to the direction of incident polarization. In the absence of media magnetization—and in the absence of the Kerr effect—both beams coming out of the polarizing beam-splitter will receive the same amount ...