High density digital videodisc using 635 nm laser diode

By developing a high resolution pick-up using a red laser diode with a wavelength of 635 nm and by examining the disc parameters, we have developed a CD-ROM which has a recording density four times that of existing CDs. The track pitch of this CD-ROM is 0.85 /spl mu/m and the recording linear velocity is 0.7 m/s. With these disc parameters, a storage capacity of 2.2 GB was obtained. We recorded digital motion pictures with a data transfer rate of 4 Mbps onto the disc and succeeded in the realization of a high quality digital videodisc with one hour of playback time.<
>