| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a good spot characteristic for any media when coma aberration correction is conducted for a plurality of optical recording media having different wavelengths being used and different substrate thicknesses while conducting a lens tilt driving. <P>SOLUTION: When media of a blue system, a DVD system and a CD system are tilted for 1 degree, generated coma aberration are in the order of 0.22λrms, 0.14λrms and 0.09λrms, respectively. However, when an objective lens satisfies ¾CLx/CDx¾≥1, where CDx(x=1, 2 and 3) are least square error values (unit;λrms) of third coma aberration components being generated per unit angle when the substrates of the media are tilted; and CLx(x=1, 2 and 3) are least square error values (unit;λrms) of third coma aberration components being generated per unit angle when the objective lens is tilted while media are light converged and illuminated, coma aberration due to the tilt of a medium is corrected by lens tilt. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
