JP2007157288A5 - - Google Patents

Claims (4)

A light source that emits a light beam having a wavelength of at least 400 to 415 nm; and an imaging optical system that has a numerical aperture of 0.6 or more and condenses the light beam emitted from the light source on a signal recording surface of an optical disc. In an optical pickup having an optical system and reproducing information from an optical disc,
The spectrum width including 50% of the energy of the light beam emitted from the light source is W (nm), the chromatic aberration of the optical system is C (μm / nm), and the wavelength of the light beam emitted from the light source is L. An optical pickup satisfying the formula (1) where NA is the numerical aperture of the imaging optical system.
0.15 <(W × C) / (L / NA ² ) <0.5 (1) 2. The optical pickup according to claim 1, wherein the optical system has a chromatic aberration of 0.29 to 1.0 [mu] m / nm. A light source that emits a light beam having a wavelength of at least 400 to 415 nm; and an imaging optical system that has a numerical aperture of 0.6 or more and condenses the light beam emitted from the light source on a signal recording surface of an optical disc. In an optical pickup having an optical system for reproducing and recording information on an optical disc,
The spectral width including 50% of the energy of the light beam emitted from the light source is W (nm), and the difference in wavelength of the light beam emitted from the light source during reproduction and recording is J (nm). When the chromatic aberration of the optical system is C (μm / nm), the wavelength of the light beam emitted from the light source is L (nm), and the numerical aperture of the imaging optical system is NA, Equation (2) and An optical pickup that satisfies Equation (3).
0.15 <(W × C) / (L / NA ² ) <0.5 (2)
0.15 <(J × C) / (L / NA ² ) <0.5 (3) 4. The optical pickup according to claim 3, wherein the optical system has a chromatic aberration of 0.29 to 1.0 [mu] m / nm.