[OPTICAL REVIEW Vol. 5, No. 6 (1998) 348-351]
Optical Super-Resolution Pickup Using a Liquid Crystal Shutter for CAD-MSR Magnetooptical Disk
Seiji MURATA, Shigeki HORI, Yoshihisa SUZUKI and Satoshi SUMI
Hypermedia Research Center, Sanyo Electric Co., LTD., 180, Ohmori, Anpachi-cho, Anpachi-gun, Gifu, 503-0195 Japan
(Received August 28, 1998; Accepted September 9, 1998)
We demonstrated characteristics of an optical super-resolution pickup using a liquid crystal (LC) shutter as a shading plate. The problem of laser power loss was solved by an LC shutter which was turned off for writing and turned on for reading. Combining this with CAD-MSR disk, we obtained good signals of high-density recording. This combination increases efficiency of laser power and does not require a slit to eliminate side-lobes. The laser power efficiency for writing is as high as 34% and linear bit density reaches 0.255 mm/bit even with a wavelength of 680 nm and an objective lens NA of 0.60.
Key words : optical pickup, magnetooptical disk, super resolution, liquid crystal shutter, CAD-MSR