Abstract: The present application discloses detection lens provided with lens portion and flange portion including first surface connected to lens portion and second surface opposite to first surface. Flange portion includes base along optical axis of lens portion, and first to fourth projections projecting from base. First and second projections are point-symmetric around optical axis. Third and fourth projections are point-symmetric around optical axis. Flange portion excludes projection extending beyond second surface. First projection includes first intersecting surface which intersects with first axis. Second projection includes second intersecting surface which intersects with first axis. Third projection includes third intersecting surface which intersects with second axis. Fourth projection includes fourth intersecting surface which intersects with second axis. First distance between first and second intersecting surfaces is longer than second distance between third and fourth intersecting surfaces.

Abstract: The present application discloses detection lens provided with lens portion and flange portion including first surface connected to lens portion and second surface opposite to first surface. Flange portion includes base along optical axis of lens portion, and first to fourth projections projecting from base. First and second projections are point-symmetric around optical axis. Third and fourth projections are point-symmetric around optical axis. Flange portion excludes projection extending beyond second surface. First projection includes first intersecting surface which intersects with first axis. Second projection includes second intersecting surface which intersects with first axis. Third projection includes third intersecting surface which intersects with second axis. Fourth projection includes fourth intersecting surface which intersects with second axis. First distance between first and second intersecting surfaces is longer than second distance between third and fourth intersecting surfaces.

Abstract: An optical pickup includes a lens holder; an objective lens provided on the lens holder and having an effective region for collecting light from a light source and an edge located outer to the effective region; and a lens protector provided on the lens holder. The lens protector protrudes toward an optical disc more than the objective lens. The edge of the objective lens includes a convexed portion protruding toward the optical disc. An apex of the effective region of the objective lens protrudes toward the optical disc more than the convexed portion of the edge. A straight line connecting a part of the edge of the objective lens and a part of the lens protector is closer to the optical disc than the apex of the effective region of the objective lens.

Abstract: An optical pickup includes a lens holder; an objective lens provided on the lens holder and having an effective region for collecting light from a light source and an edge located outer to the effective region; and a lens protector provided on the lens holder. The lens protector protrudes toward an optical disc more than the objective lens. The edge of the objective lens includes a convexed portion protruding toward the optical disc. An apex of the effective region of the objective lens protrudes toward the optical disc more than the convexed portion of the edge. A straight line connecting a part of the edge of the objective lens and a part of the lens protector is closer to the optical disc than the apex of the effective region of the objective lens.

Abstract: An optical apparatus according to the present invention comprises an optical base having a bonding surface, and an optical component fixedly bonded to the bonding surface with an adhesive. The optical base has an open hole formed in the bonding surface. The open hole is filled with the adhesive. The optical component contacts the open hole so that a part of the open hole is left unclosed.