| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device that prevents the level of tracking error signals from lowering due to eccentricity of an optical recording medium even when either one of optical recording mediums different in recording density is used. SOLUTION: Assuming that (a) is a distance from a first light source to a first grating, that (b) is a distance from a second light source to a second grating, that I and J are a first and a second prescribed grating pitch respectively and that λ1, λ2 are the wavelength of a first and a second laser beam respectively, the device nearly satisfies the inequility of λ1/λ2>(I.b)/(J.a). |
