Fujinon Corporation

Fuji Photo Optical Co., Ltd.

Fujifilm Corporation

Toshiaki Katsuma

Yu Kitahara

Tetsuya Ori

Masao Mori

Toru Ito

Taro Asami

Masato Kondo

Ryoko Otomo

Hiromitsu Yamakawa

Yoko Yamamoto

Makoto Oomura

Masato Kawabata

Kaneyoshi Yagi

Takayuki Saito

Nagayoshi Hirano

Katsuo Katagiri

Hajime Yamanaka

Koichi Noguchi

An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. When a curvature radius of an object-side surface of the fourth lens is Rand a curvature radius of an image-side surface of the fourth lens is Rand an Abbe number of the material of the third lens for d-line is &#x3bd;dand an Abbe number of the material of the fifth lens for d-line is &#x3bd;dthe following conditional formulas (1) and (6) are satisfied:&#x2212;0.61&#x3c;(8+9)/(8&#x2212;9)&#x3c;0.44 &#x2003;&#x2003;(1); and38.1&#x3c;&#x3bd;3+&#x3bd;5&#x3c;45.1 &#x2003;&#x2003;(6).

Imaging lens

An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. When a curvature radius of an object-side surface of the fourth lens is R, and a curvature radius of an image-side surface of the fourth lens is R, and an Abbe number of the material of the third lens for d-line is &#x3bd;d, and an Abbe number of the material of the fifth lens for d-line is &#x3bd;d, the following conditional formulas (1) and (6) are satisfied:&#x2212;0.61&#x3c;(R8+R9)/(R8&#x2212;R9)&#x3c;0.44&#x2003;&#x2003;(1); and38.1&#x3c;&#x3bd;d3+&#x3bd;d5&#x3c;45.1&#x2003;&#x2003;(6).

An imaging lens substantially consists of five lenses of a first lens having a meniscus shape with its convex surface facing an object side and negative refractive power, a second lens having negative refractive power, and the image-side surface of which has a convex shape facing an image side in the vicinity of an optical axis, a third lens having positive refractive power, a stop, a fourth lens having positive refractive power, and a fifth lens having negative refractive power. At least one of the surfaces of the first lens through the fifth lens is aspherical. A predetermined conditional formula about a distance on the optical axis from an object-side surface of the first lens to an image plane and a distance on the optical axis from the object-side surface of the first lens to the image-side surface of the second lens is satisfied.

Imaging lens and imaging apparatus

An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. When a curvature radius of an object-side surface of the fourth lens is R8, and a curvature radius of an image-side surface of the fourth lens is R9, and an Abbe number of the material of the third lens for d-line is &#x3bd;d3, and an Abbe number of the material of the fifth lens for d-line is &#x3bd;d5, the following conditional formulas (1) and (6) are satisfied:&#x2212;0.61&#x3c;(8+9)/(8&#x2212;9)&#x3c;0.44&#x2003;&#x2003;(1); and38.1&#x3c;&#x3bd;3+&#x3bd;5&#x3c;45.1&#x2003;&#x2003;(6).

An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. An object-side surface of the second lens is concave, and an object-side surface of the third lens is concave. A predetermined conditional formula about a combined focal length of the fourth lens and the fifth lens is satisfied.

An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. An object-side surface of the second lens has a shape having negative refractive power at a center, and including a part having positive refractive power in an area between the center and an effective diameter edge, and having negative refractive power at the effective diameter edge (concave shape facing the object side), and the refractive power at the effective diameter edge being weaker than the refractive power at the center. Further, an object-side surface of the third lens is convex toward the object side. Further, a predetermined conditional formula about a combined focal length of the first lens, the second lens and the third lens is satisfied.

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:&#x2212;0.90&#x3c;&#x3c;&#x2212;0.45&#x2003;&#x2003;(1)0.70&#x3c;&#x3c;1.40&#x2003;&#x2003;(2)where Rdenotes a radius of curvature (mm) of a light source side surface near an optical axis,

Objective lens, optical pickup device, and optical recording/reproducing apparatus

An objective lens consists of a single lens element, and has a light source side surface formed into a convex surface having a large curvature and an optical recording medium side surface has a small curvature. The both surfaces are aspheric surfaces. Also, the objective lens satisfies the following expressions (1) to (3):0.7&#x3c;NA&#x3c;0.98&#x2003;&#x2003;(1)0.70&#x3c;&#x3c;1.40&#x2003;&#x2003;(2)0.48&#x3c;X&#x3c;0.55&#x2003;&#x2003;(3).where NA denotes a numerical aperture of the objective lens on an optical recording medium side,

Objective lens, optical pickup device having the same, and recording and/or reproducing apparatus for optical recording medium, equipped with the optical pickup device

An objective lens consists of a single lens element. A light source side surface is formed into a convex surface having a large curvature, and an optical recording medium side surface has a small curvature. The both surfaces are formed into aspheric surfaces. Also, the objective lens satisfies the following expressions (1) to (3):0.70&#x3c;NA&#x3c;0.98&#x2003;&#x2003;(1)0.70&#x3c;d/f&#x3c;3.00&#x2003;&#x2003;(2)0.50&#x3c;&#x3c;0.80&#x2003;&#x2003;(3)

An objective lens for converging light emitted from a light source on an optical recording medium to record and reproduce information consists of a single lens having at least one aspheric surface. The following conditional expressions (1) to (3) are satisfied:&#x2266;1.75&#x2003;&#x2003;(1)0.5&#x3c;&#x3c;0.6&#x2003;&#x2003;(2)0.8&#x3c;/()&#x3c;1.0&#x2003;&#x2003;(3)where

A molding material is heated and pressed plural times when molded is an optical element having a radius of curvature smaller than a radius of a sphere having the same volume as the optical element. When such an optical element is molded, a closed space is formed between a molding material and a transfer surface of a mold in a state where the molding material is placed thereon. Thus, an appearance defect such as a recess is easily generated on the molded optical element. However, since the molding material is molded plural times, it is possible to place the molding materials on the transfer surfaces of the molds after a size of the closed space is adjusted so as not to generate the appearance defect prior to each heating/pressing process. Thereby, it is possible to suppress generation of an appearance defect in the molded optical element.

Optical element molding method and optical element

An objective optical system is formed of a diffractive optical element with a diffractive surface formed on a virtual plane 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 that include 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 by varying the distance between the diffractive optical element and the objective lens with the recording medium being used. The objective optical system 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 that provides the three light beams.

Objective optical system and optical pickup device using it

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.

Objective optical system for optical recording media and optical pickup device using it

A laser beam output from a semiconductor laser light sourceis transmitted through a cover glassin the optical axis Z direction, is incident on a molded lensin a state of divergent rays, is converted into convergent rays by the molded lens, and is applied onto a recording faceof the optical recording medium. A diaphragmis arranged. An area of each lens surface onto which a luminous flux of the laser beam restricted by the diaphragmis applied corresponds to an effective area. The following expression (1) is satisfied:&#x2267;0.04 mm&#x2003;&#x2003;(1)

Molded lens

A beam focusing lens having an optical axis for focusing at a point of focus a light beam having different angles of divergence in orthogonal directions perpendicular to the optical axis consists of one or two lens components, each of which may be a single lens element and made of plastic and each of which has positive refractive power. At least one lens surface is an anamorphic aspherical surface that is not a cylindrical surface, that has no cross-section perpendicular to the optical axis that is circular with a finite radius of curvature, and that is defined by a particular aspherical equation. Another lens surface may be a cylindrical aspherical surface defined by another particular aspherical equation. The beams focusing lens may satisfy certain conditions related to optical element spacings, refractive index of a single lens element, and magnifications, and may focus light from a semiconductor laser into an optical fiber.

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Tokyo, Japan

Toshiaki Katsuma