Patent ID: 7911923

Claim:
A complex objective lens for condensing a light beam onto an information recording surface of an optical disk having a base, comprising: an optical element having a relief structure on a surface thereof, and a refraction type lens, thereby condensing a first light beam having a wavelength λ 1 in a range of 390 nm to 415 nm and a second light beam having a wavelength λ 2 in a range of 630 nm to 680 nm onto respective information recording surfaces that are different from each other, wherein the optical element has a stepped cross-section, a height of the stepped cross-section being an integral multiple of a unit level difference d 2 , and the unit level difference d 2 gives a difference in optical path length longer than 1 wavelength to the first light beam and gives a difference in optical path length shorter than 1 wavelength to the second light beam, so that the unit level difference d 2 substantially adds an optical path length to the first light beam and substantially subtracts an optical path length from the second light beam.