DETECTION LENS, LENS UNIT, OPTICAL PICKUP DEVICE, OPTICAL DISC DEVICE, COMPUTER, OPTICAL DISC PLAYER, AND OPTICAL DISC RECORDER

摘要

The present application discloses a detection lens provided with: a lens part; and a flange part including a first surface to which the lens part is connected and a second surface located opposite the first surface. The flange part includes a base part arranged along the optical axis of the lens part, and first through fourth protruding parts that protrude from the base part. The first and second protruding parts are point-symmetrical about the optical axis. The third and fourth protruding parts are point-symmetrical about the optical axis. The flange part does not have a portion that protrudes beyond the second surface. The first protruding part includes a first intersecting surface that intersects the first axis. The second protruding part includes a second intersecting surface that intersects the first axis. The third protruding part includes a third intersecting surface that intersects the second axis. The fourth protruding part includes a fourth intersecting surface that intersects the second axis. The first distance between the first intersecting surface and the second intersecting surface is greater than the second distance between the third intersecting surface and the fourth intersecting surface.