Patent ID: 7123553
Filing Date: 2006-10-17
Classification: G11B

Abstract:
1. A lens support mechanism comprising: a semiconductor laser for emitting a laser beam; an enclosure to which the semiconductor laser is fixed and located; a lens disposed coaxially with the laser beam emitted from the semiconductor laser; a first cylindrical member formed in a cylindrical shape so as to fix and locate the lens at the inner surface thereof; and a second cylindrical member fitted to the first cylindrical member on a side of the lens opposite at the semiconductor laser and formed so as to be fixed to the enclosure; wherein the second cylindrical member has a linear expansion coefficient substantially the same as the linear expansion coefficient of the enclosure, wherein a shift variation Δy per unit temperature of a distance y from a position at which the first cylindrical member and the second cylindrical member fit to each other to a position at which the lens is fixed to the first cylindrical member satisfies substantially Relation (1) below: where Δx=αx, Δy=βY, Δz=γz Δfb: a back focus variation per unit temperature of the lens, α: a linear expansion coefficient of the enclosure (unit:/K), β: a linear expansion coefficient of the first cylindrical member (unit:/K), γ: a linear expansion coefficient of a stem provided to the semiconductor laser (unit:/K), x: a distance from a reference surface for attachment of the semiconductor laser to a position at which the first cylindrical member and the second cylindrical member fit to each other, and z: a distance from a reference surface for attachment of the semiconductor laser to an emission point of the semiconductor laser.