Young-man Ahn

One Beam Optical Head for High-Density Optical System with Eight Segment Photodiode.

We propose a one-beam optical head for groove-only high-density optical system. Using an eight-segment photodiode with a new detection method, the cross-talk in the wobble signal and the offset of track error signal can be reduced.

Measurement of thermal conductivities of SiN and TbFeCo films

The effective thermal conductivities of SiN and TbFeCo thin films were measured by comparing the length and width of a polarizing microscope image of thermo-magnetically written domains with those of calculated isotherms for the trilayer structure of substrate/Si/sub 3/N/sub 4//Tb/sub 22/Fe/sub 70/Co/sub 8//Si/sub 3/N/sub 4/. The resulting data were applied to the quadrilayer structure of substrate/Si/sub 3/N/sub 4//Tb/sub 22/Fe/sub 70/Co/sub 8//Si/sub 3/N/sub 4//Al, and the length of the calculated isotherms turned out to agree with that of the written domain.