| 摘要 |
This invention is directed to an optical pickup apparatus, condensing optical system, and optical element which can at least reproduce and/or record information from/on a first optical information recording medium having a protective substrate thickness t1 by using a light beam of a first wavelength lambda1 emitted from a first light source, and reproduce and/or record information from/on a second optical information recording medium having a protective substrate thickness t2 (t2>=t1) by using a light beam of a second wavelength lambda2 (lambda2>lambda1) emitted from a second light source. The optical pickup apparatus of the invention includes a first phase modulator which gives a diffraction effect to only the light beam of the wavelength lambda1 on at least one optical surface, of a plurality of optical surfaces of a plurality of optical elements arranged on a common optical path through which the light beam of the first wavelength lambda1 and the light beam of the second wavelength lambda2 pass, and a second phase modulator which gives a diffraction effect to only the light beam of the wavelength lambda2 on at least one of the remaining optical surfaces. Each of the first phase modulator and second phase modulator has staircase-like discontinuous parts, each formed from a predetermined number of stepped portions, formed concentrically around an optical axis at the pitch defined by an optical path difference function.
|
