Patent ID: 7889621
Filing Date: 2011-02-15
Classification: G02B,G11B

Abstract:
1. An objective lens device comprising: a first objective lens having a first numerical aperture, which can condense light into a disc-shaped first optical recording medium including a first cover layer of first thickness; a second objective lens having a second numerical aperture which is smaller than said first numerical aperture, which can condense light into a disc-shaped second optical recording medium including a second cover layer of second thickness which is thicker than said first thickness; a third objective lens having a third numerical aperture which is smaller than said second numerical aperture, which can condense light into a disc-shaped third optical recording medium including a third cover layer of third thickness which is thicker than said second thickness; and a lens holder configured to integrally hold said first, second, and third objective lenses, wherein when a mechanical vibration system including said first objective lens, second objective lens, third objective lens, and said lens holder resonates, said third objective lens is disposed at a position near the anti-node of vibration of the vibration system as compared with said first objective lens and said second objective lens.