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Light intensity modulated direct overwrite (LIMDOW) is a technology used to improve the data-writing speed from a system's main memory to a CD-ROM, a process referred to as magnetic-optical (MO) technology. LIMDOW is used to improve the performance of magneto-optical devices, serving as a feasible alternative to previous generation hard disk drives because of its performance and cost of ownership.
LIMDOW technology evolved in the second half of 1997. The working principle behind LIMDOW disk drives remains the same as that of a standard magneto-optical drive, but it differs in that it modulates the laser’s intensity for both erase and copy processes, thus completing the write operation onto the disk in a single rotation.
In LIMDOW technology, a disk is designed with two built-in magnetic layers, which are positioned on the back of the reflective writing surface. This surface is more intelligent than that found in magneto-optical drives because it has the ability to acquire its magnetism from one of the magnetic layers when it is heated up to a certain temperature. If the layer is heated up beyond that temperature, the surface will acquire polarity from the other magnetic layer.
In order to write the data onto a disk, the magneto-optical drive’s laser pulses between higher and lower powers. The surface always heats up more at a high power and acquires the charge form the North Pole magnetic layer. When the surface is heated up less at lower power, it acquires a charge from the South Pole magnetic layer. Because of this, the write process is completed in a single rotation.
LIMDOW implementations include computer-aided design document imaging and archiving. It offers search speeds of less than 15 milliseconds and a data transfer rate greater than or equal to 4Mbps. LIMDOW magneto-optical technology is also implemented for audio-visual and multimedia applications. LIMDOW has not only made magneto-optical competitive on write times, but has also lead the way toward high-capacity magneto-optical disks. The positioning of the magnetic surface next to the writing surface helps to perform magnetic writing at a higher resolution.