摘要:
An objective lens for converging light emitted from a light source onto an optical recording medium to record and reproduce information consists of a single lens that has at least one aspheric surface. The following conditional expressions (1) and (2) are satisfied: −0.90
摘要:
An objective lens 8 consists of a single lens element. A light source side surface 8a is formed into a convex surface having a large curvature, and an optical recording medium side surface 8b has a small curvature. Also, the objective lens satisfies the following expressions (1) and (2) ΦA/ΦB
摘要:
An objective optical system for focusing light from a light source onto at least two different types of optical recording media having different substrate thicknesses in order to record or reproduce information on the optical recording media includes at least two lens groups arranged along an optical axis for focusing light of each one of two wavelengths that are the same or very nearly the same from the light source on a different one of the at least two different types of optical recording media, such as an AOD and a BD, having different substrate thicknesses. The separations of the two lens groups are different when light of each wavelength is used, and four different types of optical recording media with different substrate thicknesses may be used. An optical pickup device includes the objective optical system, the recording media, and a light source supplying the light of the two wavelengths.
摘要:
An objective optical system focuses light from a light source onto at least two different types of optical recording media having different substrate thicknesses in order to record or reproduce information on the optical recording media by using a variable refractive power element and an objective lens. The variable refractive power element may be a liquid crystal element with concentric zones that serves as a transparent plate having no convergence effect when no voltage is applied when selecting an AOD, DVD, or CD and as a converging lens when a voltage is applied when selecting a BD. Alternately, the variable refractive power element may electrically vary the refractive index of a nanoparticle dispersion or at least one liquid of a two-liquid lens element. A diffractive optical element may be used to assist in focusing light to four recording media. An optical pickup device includes the objective optical system.
摘要:
An objective optical system is formed of a diffractive optical element with a diffractive surface formed on a planar ‘virtual surface’ (i.e., a surface that would be planar but for the diffractive structure) and an objective lens for focusing three collimated light beams of three different wavelengths at three different numerical apertures onto desired positions of three different recording media with substrates of different thicknesses, such as an AOD, a DVD, and a CD, that introduce different amounts of spherical aberration in the focused beams. The objective optical system provides compensating spherical aberration to the three light beams while keeping equal the distance between the diffractive optical element and the objective lens, and focuses second-order diffracted light of one wavelength and first-order diffracted light of the other two wavelengths. An optical pickup device includes the objective optical system, the recording media, and a light source supplying the three light beams.
摘要:
An objective lens is formed as an objective lens element with a diffractive surface on one side. The objective lens focuses a collimated light beam of a first wavelength diffracted by the objective lens onto a first recording medium, a collimated light beam of a second wavelength diffracted by the objective lens onto a second recording medium, and a diverging light beam of a third wavelength diffracted by the objective lens onto a third recording medium. The three light beams are focused at three different working distances from the objective lens and the diffraction orders of the diffracted light of two of the light beams is the same. The objective lens satisfies certain conditions related to the shortest of the three different working distances, the focal length of the objective lens element at the shortest of the three wavelengths, and the thickness of the objective lens.
摘要:
An objective lens consists of two lens elements of different materials that are cemented. The lens surfaces that are cemented includes a phase function so that the cemented surface forms a optical diffractive surface that enables the objective lens to focus incident light of three different wavelengths with different numerical apertures onto different optical recording media. Three conditions are satisfied so as to achieve optimum imaging. The optical diffractive surface may be shaped so that the order of the diffracted light of the shortest wavelength λ1 having the largest diffracted intensity is different from the order of the diffracted light of the second wavelength λ2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength λ1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength λ3 having the largest diffracted intensity.
摘要:
A laser beam output from a semiconductor laser light source 1 is transmitted through a cover glass 2 in the optical axis Z direction, is incident on a molded lens 4 in a state of divergent rays, is converted into convergent rays by the molded lens 4, and is applied onto a recording face 5 of the optical recording medium. A diaphragm 3 is arranged. An area of each lens surface onto which a luminous flux of the laser beam restricted by the diaphragm 3 is applied corresponds to an effective area. The following expression (1) is satisfied: d1−d0≧0.04 mm (1) where d0 denotes an effective aperture of one of the lens surfaces, and d1 denotes an outer diameter of the one of the lens surfaces.
摘要:
An objective lens consists of two lens elements of different materials that are cemented. The lens surfaces that are cemented includes a phase function so that the cemented surface forms a optical diffractive surface that enables the objective lens to focus incident light of three different wavelengths with different numerical apertures onto different optical recording media. Three conditions are satisfied so as to achieve optimum imaging. The optical diffractive surface is shaped so that the order of the diffracted light of the shortest wavelength λ1 having the largest diffracted intensity is zero and different from the order of the diffracted light of the second wavelength λ2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength λ1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength λ3 having the largest diffracted intensity.
摘要:
An objective optical system includes a diffractive optical element on the light source side of an objective lens for focusing incident light of three different wavelengths with two different numerical apertures onto three different optical recording media. The diffractive optical element is formed of two lens elements made of different materials that are cemented together at a diffractive surface. Three conditions are satisfied so as to achieve optimum imaging. The diffractive surface may be shaped so that the order of the diffracted light of the shortest wavelength λ2 having the largest diffracted intensity is different from the order of the diffracted light of the second wavelength λ2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength λ1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength λ3 having the largest diffracted intensity.