Magneto-optical drive
During reading, a laser projects a beam on the disk and, according to the magnetic state of the surface, the reflected light varies due to the magneto-optic Kerr effect.
During recording, laser power is increased to heat the material to the Curie point in a single spot.
This enables an electromagnet positioned on the opposite side of the disc to change the local magnetic polarization.
The electromagnet reverses polarity for writing, and the laser is pulsed to record spots of "1" over the erased region of "0".
[6] In 1996, Direct Overwrite technology was introduced for 90 mm discs eliminating the initial erase pass when writing.
By default, magneto-optical drives verify information after writing it to the disc, and are able to immediately report any problems to the operating system.
During a read cycle, the laser is operated at a lower power setting, emitting polarized light.
The optical libraries could also manually be used on a Windows 2000/XP machine by selecting and ejecting discs under the Computer Management icon's Removable Storage Service, but this is cumbersome in practice.
LIMDOW drives that shipped in the second half of 1997 has search speeds of less than 15 ms and data transfer rates in excess of 4 Mbit/s, which are fast enough for storing audio and streaming MPEG-2 video.
As of August 2021[update], Sony continues to manufacture one type of blank MiniDisc available only in Japan; the rest of the world only has access to dwindling new stock from vendors on sites such as eBay or Amazon.
TEAC & TASCAM continued to manufacture MiniDisc decks up until 2020 while Sony ceased production of hardware in 2013.
No laser or heating is involved; a simple infrared LED is used to follow the optical tracks, while a magnetic head touches the recording surface.
At the Consumer Electronics Show in January 2004, Sony revealed a 1 gigabyte capacity MiniDisc called Hi-MD.
As with all removable storage media, the advent of cheap CD and DVD drives and flash memory has made them largely obsolete.
Magnetic tape formats like LTO have far surpassed MO media for high capacity enterprise-grade backup storage.
[12] It was demonstrated that extremely low light intensities in the range of 1 μWcm−2 can be used to read/write magnetic information in femtosecond (10−15 s timescales) allowing high-speed, high-density data storage in principle.
