BEAM SHAPING OPTICAL DEVICE, OPTICAL HEAD, AND OPTICAL INFORMATION MEDIUM DRIVE DEVICE

摘要

An object of the present invention is to suppress the deterioration of a collimation quality resulting from a temperature change. A lens surface of a collimating lens 2 closer to a light source 20 is in contact with a retracted surface 3a at one end surface of a barrel 3. On a projecting surface at an outer side of the one end surface of the barrel 3, grooves 11 are formed at a plurality of positions symmetric with respect to an optical axis O. An adhesive 15 depositing in the grooves 11 are applied to the outer circumferential surface of the collimating lens 2 to fix the collimating lens 2 in the barrel 3. Since the grooves 11 are formed to be shallower than the retracted surface 3a, the adhesive 15 does not intrude onto the retracted surface 3a. The barrel 3 is pressed against a wall surface formed in the inner circumferential surface of a barrel holder main portion 5 and having a V-shaped cross section by a leaf spring 13, thereby being held at a specified position in the barrel holder main portion 5. An amount of change ”L in distance from a reference surface to a held position of the collimating lens 2 per unit temperature is set to conform to a sum of an amount of change ”t in the movement of the light source 20 from the reference position per unit temperature and an amount of change ”f of the back focus of the collimating lens 2 per unit temperature.