Patent ID: 7236313

Claim:
A ring zonal phase correction lens for use with a laser, the lens being made of resin comprising a refraction face which is formed on at least one of a first lens face and a second lens face, the refraction face comprising: three or more ring zonal shaped refraction curved surfaces which are structurally formed to be adjacent to each other through step portions structurally formed in an optical axis direction for correcting a phase of a laser beam emitted from the laser by respective ring zonal shaped refraction curved surfaces; wherein the step portion is structurally formed such that a lens thickness of an outer ring zonal shaped refraction curved surface becomes thicker than a lens thickness of an inner ring zonal shaped refraction curved surface and the step portion is structurally formed at a half or more outer area location of an effective radius of the refraction face; wherein a variation amount of tertiary spherical aberration due to temperature variation is set to be ½ or less than a variation amount of tertiary spherical aberration due to temperature change in a lens whose refraction face is formed based on only a formula expressing an innermost aspheric surface without being divided.