In Sony's system (used on their proprietary Optical Disc Archive system which is predicated on Archival Disc, itself primarily based on Blu-ray) the drive has four optical pickups, two on every facet of the disc, with each pickup having two lenses for a complete of 8 lenses and Free Slots laser beams. The ExpressCard standard specifies two form components, ExpressCard/34 (34 millimetres (1.3 in) wide) and ExpressCard/54 (fifty four mm (2.1 in) extensive, in an L-shape)-the connector is the same on both (34 mm large).

Both layers are accessible from the same aspect, free online slots however require the optics to change the laser's focus. Because the depth of the pits is approximately one-quarter to one-sixth of the laser's wavelength, the mirrored beam's section is shifted in relation to the incoming beam, free slots causing mutual destructive interference and Slots online lowering the mirrored beam's depth. In Zen's system (developed together with Sanyo and licensed by Kenwood), Free slots no download a diffraction grating is used to cut up a laser beam into 7 beams, which are then targeted into the disc; a central beam is used for focusing and free slots online tracking the groove of the disc leaving 6 remaining beams (three on either facet) which might be spaced evenly to learn 6 separate portions of the groove of the disc in parallel, successfully growing learn speeds at decrease RPMs, decreasing drive noise and stress on the disc.

Zen Technology and Sony have developed drives that use a number of laser beams simultaneously to learn discs and write to them at increased speeds than what could be doable with a single laser beam. Disc recording is restricted to storing recordsdata playable on consumer appliances (films, music, etc.), comparatively small volumes of data (e.g. a typical DVD holds 4.7 gigabytes, however, increased-capability formats such as multi-layer Blu-ray Discs exist) for native use, and data for distribution, however only on a small scale; mass-producing large numbers of identical discs by pressing (replication) is cheaper and faster than individual recording (duplication).