摘要:
A positive first lens group G1, a negative second lens group G2, an aperture diaphragm St, a positive third lens group G3, and a positive fourth lens group G4 are sequentially arranged, and a movement of the lens groups and the aperture diaphragm St during zooming is optimized in combination with an appropriate conditional expression. During zooming, a position of the aperture diaphragm St on an optical axis at a wide-angle end is closer to an image plane than that at a telephoto end, and a space on the optical axis at the wide-angle end between the aperture diaphragm St and the third lens group G3 is larger than that at the telephoto end, thereby suppressing the length of the whole lens. Also, heights of rays passing through the first lens group G1 are lowered, thereby suppressing the lens diameter of the first lens group G1.
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:
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.
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:
A zoom lens includes a function of preventing blurring of an image due to movements, such as shaking of the zoom lens, by moving the second lens group, in order from the object side, orthogonally to the optical axis in order to correct for blurring of an image due to movements of the zoom lens. The zoom lens includes a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. The first and second lens groups move along the optical axis during zooming, as does the third lens group in all but one embodiment of the invention. The zoom lens satisfies certain conditions related to the configuration of the lens elements and lens groups of the zoom lens in order to prevent blurring and to provide a compact zoom lens having excellent correction of aberrations.
摘要:
An objective optical system for optical recording media and an optical pickup device using the objective optical system includes a holographic optical element that includes angularly-multiplexed holograms for correcting spherical aberration and/or coma aberration due to variations in substrate thicknesses of recording media and errors by tilting the holographic optical element out of the plane perpendicular to the optical axis by specified amounts. A control system determines the spherical aberration and/or coma using a control unit and outputs command signals for controlling the amount of tilt. The angularly-multiplexed holograms may change an input substantially collimated light beam to a divergent or convergent light beam except when the substrate of the optical recording media has a specified thickness. Additionally, the holographic optical element may include wavelength-multiplexed holograms to correct for chromatic aberration due to mode hopping of a semiconductor laser light source.
摘要:
A zoom optical system includes a function of preventing blurring of an image due to movements, such as shaking of the zoom optical system, by moving a lens element of the third lens group, in order from the object side, of four lens groups in a direction that is perpendicular to the optical axis in order to correct for movements of the zoom optical system that would otherwise create a blurred image. The second lens group from the object side has negative refractive power and the other three lens groups have positive refractive power. The second and fourth lens groups move along the optical axis during zooming. The zoom optical system satisfies certain conditions related to the configuration of the lens elements and lens groups of the zoom optical system in order to prevent blurring and to provide a compact zoom optical system having excellent correction of aberrations.
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 onto the optical recording media by using a different light convergence or divergence effect based on a difference in the vibrational direction of the polarization of polarized incident light. This difference may be caused by passing the light through a uniaxial crystal, such as crystallized quartz, that has its optic axis arranged to use an extraordinary ray and an ordinary ray that are subject to different refractive indexes in an objective optical system even though the rays have the same wavelength. Diffractive optics may also be used to enable excellent focusing on more than two recording media. An optical pickup optical system and an optical pickup device using this optical pickup optical system include the objective optical system.