Abstract: An objective lens for an optical pickup device is characterized in that compatibility of three types of optical discs, which are a BD, a DVD, and a CD, may be realized by a common objective lens, and a flare can be created by providing an over-spherical aberration when a third optical disc is used from a size relationship between a pitch on a central region side and a pitch on an intermediate region side across a boundary and a relationship of a direction of a step in the base structures superimposed in a central region and an intermediate region of the objective lens.

Abstract: An optical pickup apparatus including an objective lens capable of enhancing temperature characteristics and wavelength characteristics, and which enables compatibility for three types of optical discs of BDs, DVDs, and CDs by using the objective lens in common, an optical information recording and reproducing apparatus, and an objective lens suitable for it. In a first optical path difference providing structure in which at least a first basic structure and a second basic structure are superimposed on each other, an amount of a level difference in an optical axis direction can be reduced, whereby it becomes possible to suppress the lowering of a diffraction efficiency when wavelength changes. Further, in the first basic structure and the second basic structure deterioration of the spherical aberration due to the change of the refractive index of the objective lens can be corrected by utilizing a phenomenon that the wavelength of the light source rises similarly due to a rise in the environmental temperature.

Abstract: An optical pickup apparatus including an objective lens capable of enhancing temperature characteristics and wavelength characteristics, and which enables compatibility for three types of optical discs of BDs, DVDs, and CDs by using the objective lens in common, an optical information recording and reproducing apparatus, and an objective lens suitable for it. In a first optical path difference providing structure in which at least a first basic structure and a second basic structure are superimposed on each other, an amount of a level difference in an optical axis direction can be reduced, whereby it becomes possible to suppress the lowering of a diffraction efficiency when wavelength changes. Further, in the first basic structure and the second basic structure deterioration of the spherical aberration due to the change of the refractive index of the objective lens can be corrected by utilizing a phenomenon that the wavelength of the light source rises similarly due to a rise in the environmental temperature.

Abstract: An objective lens for an optical pickup device is characterized in that compatibility of three types of optical discs, which are a BD, a DVD, and a CD, may be realized by a common objective lens, and a flare can be created by providing an over-spherical aberration when a third optical disc is used from a size relationship between a pitch on a central region side and a pitch on an intermediate region side across a boundary and a relationship of a direction of a step in the base structures superimposed in a central region and an intermediate region of the objective lens.

Abstract: Provided are an objective lens with enhanced transmittance and an optical pickup apparatus which can record and/or reproduce information properly for three kinds of discs with different recording densities, even if a single lens is used as the objective lens. When all the expressions (1) to (3) are satisfied, excellent aberration characteristics can be obtained for the three kinds of discs: ?0.02?m1?0.02 (1); 0?(WD1?WD2)?1.57 m2+0.123 or 1.57 m2+0.24?(WD1?WD2)?0.7 (2); and 0?(WD1?WD3)?1.79 m3+0.333 or 1.66 m3+0.508?(WD1?WD3)?0.7 (3).

Abstract: Provided are an optical pickup apparatus and an objective lens which can record and/or reproduce information for discs with different recording densities and can realize simplification of the structure of themselves and reducing cost. When the expression (1) is satisfied, step differences of a step structure can be further reduced than those in the case that d1=?1(n?1) holds, and fine grooves corresponding to a steps structure, formed on an optical-surface transfer surface of a mold for molding the objective lens become shallow, to be easily processed. In addition, the moldability is enhanced because the material of the objective lens easily enters the inner portion of the grooves. Further, a fluctuation of a diffraction efficiency caused when wavelength of a light flux changes or temperature changes is reduced so that information can be recorded and/or reduced stably.

Abstract: An optical pickup apparatus includes: a first light source; a second light source; a light-converging optical system including a coupling lens and an objective lens; and a photodetector. The optical pickup apparatus is capable of recording and/or reproducing information by converging a light flux from each of the first and second light sources with the light-converging optical system on an information recording surface of each of first and second optical information recording media through a protective layer, and by detecting the light flux reflected from the information recording surface and passing through the light-converging optical system again, on the photodetector. The optical pickup apparatus satisfies predetermined conditions according to an optical path length from each of first and second light sources and the information recording medium, a magnification of the objective lens, and a magnification of the light-converging optical system.

Abstract: Provided are an objective lens with enhanced transmittance and an optical pickup apparatus which can record and/or reproduce information properly for three kinds of discs with different recording densities, even if a single lens is used as the objective lens. When all the expressions (1) to (3) are satisfied, excellent aberration characteristics can be obtained for the three kinds of discs: ?0.02?m1?0.02 (1); 0?(WD1?WD2)?1.57 m2+0.123 or 1.57 m2+0.24?(WD1?WD2)?0.7 (2); and 0?(WD1?WD3)?1.79 m3+0.333 or 1.66 m3+0.508?(WD1?WD3)?0.7 (3).

Abstract: Provided are an optical pickup apparatus and an objective lens which can record and/or reproduce information for discs with different recording densities and can realize simplification of the structure of themselves and reducing cost. When the expression (1) is satisfied, step differences of a step structure can be further reduced than those in the case that d1=?1(n?1) holds, and fine grooves corresponding to a steps structure, formed on an optical-surface transfer surface of a mold for molding the objective lens become shallow, to be easily processed. In addition, the moldability is enhanced because the material of the objective lens easily enters the inner portion of the grooves. Further, a fluctuation of a diffraction efficiency caused when wavelength of a light flux changes or temperature changes is reduced so that information can be recorded and/or reduced stably.

Abstract: An objective optical element for use in an optical pickup apparatus, includes two or more optical elements having a first surface having a first phase difference providing structure and a second surface having a second phase difference providing structure, wherein each of the first and second phase difference providing structures emit a diffracted light flux corresponding to each of the entering first-third light fluxes, or emit a transmitting light flux which is not applied a diffractive action corresponding to each of the entering first-third light fluxes, and the first-third light fluxes enter into the objective optical element as an almost infinite parallel light flux for information reproducing and/or recording on the first-third optical information recording media respectively.

Abstract: An optical pickup apparatus includes: a first light source; a second light source; a light-converging optical system including a coupling lens and an objective lens; and a photodetector. The optical pickup apparatus is capable of recording and/or reproducing information by converging a light flux from each of the first and second light sources with the light-converging optical system on an information recording surface of each of first and second optical information recording media through a protective layer, and by detecting the light flux reflected from the information recording surface and passing through the light-converging optical system again, on the photodetector. The optical pickup apparatus satisfies predetermined conditions according to an optical path length from each of first and second light sources and the information recording medium, a magnification of the objective lens, and a magnification of the light-converging optical system.