Abstract: There is provided an ultraviolet absorber having a strong absorptive capacity in the UVA range and an absorptive capacity in the UVB range to have an ultraviolet inhibitory effect in a wide range of wavelength, increasing in an ultraviolet absorptive capacity over the course of ultraviolet irradiation time in both the UVA and the UVB ranges and having an excellent solubility. An ultraviolet absorber comprising, as an active ingredient, a compound of General Formula I: (where —OA is an alkoxy group) that exhibits an ultraviolet A wave absorptive capacity which increases over time and that has an ultraviolet B wave absorptive capacity.

Abstract: An imaging lens includes, in order from an object side, a first lens G1, a second lens G2, a third lens G3, an aperture stop St and a fourth lens G4. The first lens is a negative lens having a meniscus shape with a convex surface directed to the object side. The second lens is a negative lens. The third lens is a positive lens having a convex surface directed to the object side. The fourth lens is a biconvex lens. The following conditional expression is satisfied: 1.5<f4/fa<2.7??(1) where fa denotes a focal length of the whole lens system, and f4 denotes a focal length of the fourth lens.

Abstract: 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.

Abstract: An antiviral preparation comprising as an active ingredient, a phorbol derivative of formula 1: wherein is R1 is —(CH2)aX(CH2)bCH3, —(CH2)cX(CH2)dYCH3, —CO(CH2)eCH3 or —(CH2)fCH3 R2 is —CO(CH2)nCH3, R3, R4 and R5 are hydrogen atom, or an aliphatic or aromatic carboxylic acid residue, X and Y are O or S, and each of a-f and n is a number, and having a specific safety index S.I.=CC50/EC50 of 10 or more wherein EC50 means a concentration at which HIV-1 induced cytopathogenic effect (CPE) in MT-4 cell is inhibited by 50%, and CC50 means a concentration at which survival of MT-4 cell in a cell proliferation test is reduced by 50%. These preparations are particularly effective for human immuno-deficiency virus (HIV).

Abstract: A color image readout lens comprises, in order from an object side: a first group comprising a positive lens convex toward the object side and a biconcave negative lens; a stop; a second group comprising one diffractive optical element that has at least one flat surface and has a diffractive structure formed on the flat surface; and a third group comprising a biconvex positive lens and a negative lens concave toward the object side.

Abstract: 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<R1/R2<?0.45??(1) 0.70<d/f<1.40??(2) where R1 denotes a radius of curvature (mm) of a light source side surface near an optical axis, R2 denotes a radius of curvature (mm) of an optical recording medium side surface near the optical axis, d denotes a thickness (mm) on an optical axis, and f denotes a focal length (mm).

Abstract: 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: N?1.75??(1) 0.5<f/f1<0.6??(2) 0.8<d/(NA·De)<1.0??(3) where N denotes a refractive index, f denotes a focal length (mm), f1 denotes a focal length (mm) of a light source side surface, d denotes a thickness (mm) on an optical axis, NA denotes a numerical aperture on an optical recording medium side, and De denotes an effective aperture (mm) of the light source side surface.

Abstract: 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.

Abstract: 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.

Abstract: 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) ?A/?B<5.0 ??(1) 7.69??A/?B+19.33×bf?/f??9.45 ??(2) where ?A denotes an effective diameter (mm) of the light source side surface of the objective lens 8, ?B denotes an effective diameter (mm) of the optical recording medium side surface of the objective lens 8, bf? denotes a back focal length (mm) of the objective lens 8, and f? denotes a focal length (mm) of the objective lens 8.

Abstract: 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<NA<0.98 ??(1) 0.70<d/f<3.00 ??(2) 0.50<g/d<0.80 ??(3) where NA denotes a numerical aperture of the objective lens on an optical recording medium side, d denotes a thickness, in mm, of the objective lens on an optical axis, and g is a distance, in mm, from a tangential plane that is perpendicular to the optical axis and is tangent to a vertex of the light source side surface of the objective lens, to a center of gravity of the objective lens.

Abstract: 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<NA<0.98 ??(1) 0.70<d/f<1.40 ??(2) 0.48<X<0.55 ??(3). where NA denotes a numerical aperture of the objective lens on an optical recording medium side, d denotes a thickness of the objective lens on an optical axis in mm, and f denotes a focal length of the objective lens in mm. X is equal to (X1?X2)·(n?1)/(NA·f), where X1 and X2 denote values relating to sag amounts in the respective surfaces, and n denotes a refractive index.

Abstract: 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 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 aberrations to the three light beams, two of which are incident on the objective optical system as collimated beams and one of which is incident as a diverging beam. 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.

Abstract: An imaging lens comprises, in order arranged from an object side: a first lens of a negative meniscus lens which is curved to be convex towards an object; a second lens of a positive lens which is curbed to be convex on an object side surface thereof; a diaphragm; a third lens which is curved to be convex towards an image; a fourth lens having a positive refractive power in the vicinity of an optical axis; and a fifth lens which is curved to be concave towards the image in the vicinity of the optical axis while being curved to convex towards the image along a circumferential edge portion on an image side surface thereof.

Abstract: A color image readout lens comprises, in order from an object side: a first group comprising a positive lens convex toward the object side and a biconcave negative lens; a stop; a second group comprising one diffractive optical element that has at least one flat surface and has a diffractive structure formed on the flat surface; and a third group comprising a biconvex positive lens and a negative lens concave toward the object side.

Abstract: 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 ?1 having the largest diffracted intensity is zero and different from the order of the diffracted light of the second wavelength ?2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength ?1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength ?3 having the largest diffracted intensity.

Abstract: 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 ?2 having the largest diffracted intensity is different from the order of the diffracted light of the second wavelength ?2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength ?1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength ?3 having the largest diffracted intensity.

Abstract: An imaging lens includes, in order from an object side, a first lens G1, a second lens G2, a third lens G3, an aperture stop St and a fourth lens G4. The first lens is a negative lens having a meniscus shape with a convex surface directed to the object side. The second lens is a negative lens. The third lens is a positive lens having a convex surface directed to the object side. The fourth lens is a biconvex lens. The following conditional expression is satisfied: 1.5<f4/fa<2.7 ??(1) where fa denotes a focal length of the whole lens system, and f4 denotes a focal length of the fourth lens.

Abstract: A lens is equipped with a reference mounting surface that is abutted to a surface of a lens support member at the time of mounting the lens, wherein the reference mounting surface is arranged between a plane which is normal to the optical axis of the lens and includes a principal point on the incident light side of the lens and a plane which is normal to the optical axis of the lens and includes a principal point on the outgoing light side of the lens.

Abstract: An ultraviolet ray protection agent including a compound having an ultraviolet ray protection effect as an active ingredient. The compound is expressed by general formula I?: wherein X represents NH or O; Y? represents a vinyl group substituted by a methyl group or a phenyl group, or a phenyl group substituted by a methoxy group or a fluorine atom, or a naphthyl group; and Z represents a phenyl group substituted by a methyl group, a carboxyl group or a nitro group, or a naphthyl group. The compound represented by the general formula I? includes both novel compounds of the present invention and known compounds. The ultraviolet ray protection agent of the present invention offers outstanding ultraviolet ray protection effectiveness and is very safe.