DECEMBER 17--Matsushita Electric Industrial Co. Ltd. (Osaka, Japan; www.panasonic.coljp/global/top.html), known for its Panasonic brand of consumer-electronic and digital-communications products, has developed an innovative rewriteable dual-layer optical-disk technology that uses a blue laser. In addition, Matsushita announced development of an advanced 50-Gbyte optical disk that fully utilizes this new technology. These new developments make possible interchangeable and large-capacity storage media with superior searching and operating capabilities. Until these newly announced developments by Matsushita, using a blue laser effectively for dual-layer optical-disk operations has not been deemed possible.
The new optical disk achieves 50-Gbyte rewrite capacity on one side of a dual-layer disk using an ultrathin recording layer for the half-transparent first recording layer (achieving more than 50% transmittance with a 6-nm recording film thickness) and superior recording and playback characteristics on the second recording layer. This represents a capacity more than 10 times larger than conventional rewriteable optical disks. The new technology also realizes a maximum recording and playback data-transfer rate of 33 Mbit/s, three times faster than conventional DVD technology. These features make it possible to record more than four hours of digital high-definition moving pictures at a data-transfer rate of 25 Mbit/s.
The new disk technology features a GeSbTe (germanium antimony tellurium) film with excellent overwrite cyclability (greater than 10,000 cycles) and high sensitivity by writing with a 10-mW blue laser light spot that matches the power level of conventional optical-disk technology. Along with a newly developed highly sensitive disk structure that creates a slight misalignment of the center holes between the first and second media, both layers can now be easily accessed from one side of the disk with highly stable tracking control.