Beam shaping optical device, optical head, and optical information medium drive unit

Abstract

A lens surface of a collimating lens closer to a light source is in contact with a retracted surface at one end surface of a barrel. On a projecting surface at an outer side of the one end surface of the barrel, grooves are formed at a plurality of positions symmetric with respect to an optical axis. An adhesive deposited in the grooves is applied to an outer circumferential surface of the collimating lens to fix the collimating lens in the barrel. Since the grooves are formed to be shallower than the retracted surface, the adhesive does not intrude onto the retracted surface. The barrel is pressed against a wall surface formed in an inner circumferential surface of a barrel holder main portion and having a V-shaped cross section by a leaf spring, thereby being held at a specified position in the barrel holder main portion. An amount of change in distance from a reference surface to a held position of the collimating lens per unit temperature is set to conform to a sum of an amount of change in movement of the light source from the reference position per unit temperature and an amount of change of back focus of the collimating lens per unit temperature.