OPTICAL PARTS, BIAXIAL ACTUATOR AND OPTICAL DISK DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To make it possible to prevent the deterioration of optical characteristics by double refraction without the deterioration of other optical characteristics, physical characteristics and mechanical performance, exclusive of the double refraction at the time of molding of optical parts by inclining the inclination of a gate at the time of injection molding with respect to a diametral direction of the optical parts. SOLUTION: An objective lens 1 consists of a lens part 2 and a flange part 3 formed on its outer periphery. The lens part 2 is a biconvex lens and both faces thereof are formed to aspherical surfaces. The flange part 3 forms a cylindrical shape projecting to an optical axis direction from the outer peripheral part of the flange lens part 2. A runner 8 is so formed that its extending direction of a runner 8 aligns to the diameter D direction of the lens part 2 of the objective lens 1 and passes the center of the lens part 2 of the objective lens 1. Also, the gate 9 is molded from the center at the front end of the runner 8 toward the outer peripheral surface of the flange part 3 of the objective lens 1. The gate 9 is so molded that its direction is aligned to the tangent T direction of the objective lens 1 and the direction of the gate 9 is inclined with the diameter D direction of the lens part 2.