Erasable memory plates work partly according to the optical and partly according to the magnetic principle.
In the Thermo Magnets Optics process, a laser beam heats the magnetic plate up to the crystallization point. At this temperature, a magnetic material loses its magnetic properties. This erases the memory. As with any magnetic disk, the data is stored by magnetic fields. To read the data, the laser beam is used, which is deflected differently by the differently polarized fields.
The Compact Disc Magneto Optical (CD-MO) is specified in the Orange Book, it is available in different sizes, it is rewritable on one and both sides, works with Constant Angular Velocity (CAV) and has a storage capacity of 128 Megabyte (MB) to 2.6 Gigabyte (GB).