Aberration correction element for use in reading and writing data on multiple types of optical recording media

Abstract

An aberration correction element including a diffraction plane that corrects a spherical aberration caused by the difference among a first optical recording medium, a second optical recording medium, and a third recording medium by transmitting first beams of light having a wavelength of λemitted from a first light source to read and write data on the first recording medium, and diffracting second beams of light having a wavelength of λemitted from a second light source to read and write data on the second recording medium, and third beams of light having a wavelength of λemitted from a third light source to read and write data on the third recording medium; and a phase shifter plane generating a spherical aberration −ΔSA having a reverse direction to a spherical aberration ΔSA generated at an objective lens optimized for the first optical recording medium according to a temperature change.