Optical Super-Resolution Pickup Using a Liquid Crystal Shutter for CAD-MSR Magnetooptical Disk

Abstract

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.