Abstract: A photochromic device having a photochromic layer including a photochromic material which exhibits absorbance in a visible region upon being sensitized by a light having a wavelength of not less than 700 nm, and an ultraviolet light blocking device for blocking an ultraviolet light from sensitizing the photochromic material in the photochromic layer. The ultraviolet light blocking device includes at least one of an ultraviolet shielding layer positioned to shield the photochromic layer from the ultraviolet light and an ultraviolet light absorber included in the photochromic layer.

Abstract: It is possible to produce a pigment-modified cyclodextrin film or fiber expected to be versatile in medicines, foods and pesticides such as packing films like wafer (for example, films to wrap food or drugs, and packages whose colors change when contained food begins to leak). It is comprised by p-methyl red of pigment-modified cyclodextrins, each made by modifying ?-cyclodextrin with p-methyl red, having a structure to be included into different ?-cyclodextrin of pigment-modified cyclodextrins than the p-methyl red, which leads the pigment-modified cyclodextrins to be highly associated between their molecules to form molecular aggregates.

Abstract: A calcium fluoride crystal produced in accordance with a method for producing calcium fluoride crystal on the basis of refining a raw material of calcium fluoride and causing crystal growth of the refined calcium fluoride, the method including a process of raising a purity of the calcium fluoride to complement the refining, wherein a transition density in crystal is not greater than 1×105/cm2, and that dispersion of transition density inside an effective portion in crystal is in a range of ±5×104/cm2. Also disclosed is an optical element to be manufactured by use of such CaF2 crystal.

Abstract: A photochromic device having a photochromic layer including a photochromic material which exhibits absorbance in a visible region upon being sensitized by a light having a wavelength of not less than 700 nm, and an ultraviolet light blocking device for blocking an ultraviolet light from sensitizing the photochromic material in the photochromic layer. The ultraviolet light blocking device includes at least one of an ultraviolet shielding layer positioned to shield the photochromic layer from the ultraviolet light and an ultraviolet light absorber included in the photochromic layer.

Abstract: A photochromic display element comprising a photochromic layer 12 containing a 4,4′-bipyridine derivative as a photochromic compound intervined between a transparent substrate 11 placed at a front surface side and a substrate 13 placed at a rear surface side. When a light containing an infrared light having a wavelength of 830 nm is irradiated, the photochromic display element exhibits the absorbance spectrum within a visible light region is reversibly changed whereby the photochromic layer 12 is colored and bleached.

Abstract: A diffraction optical element comprises a substrate, a diffraction grating formed on the substrate with a material with low ultraviolet resistance and an ultraviolet screening means arranged on the substrate at a position closer to the incident light receiving side of the optical element relative to the diffraction grating. The ultraviolet screening means comprises a dielectric multilayer film and is formed on the other side of the substrate than the side carrying the diffraction grating. Alternatively, the ultraviolet screening means may be provided as a separate member from a diffraction optical element and arranged at a position closer to the incident light receiving side of the diffraction optical element in an optical system.

Abstract: Disclosed is a method of producing fluoride crystal, wherein the method includes a dehydrating step for dehydrating a raw material of fluoride by heating a crucible being adapted to accommodate a raw material of fluoride therein and having an exhaust mechanism for exhausting an inside gas of the crucible, and a exhausting step for exhausting, in the dehydrating step, an inside gas of the crucible by use of the exhaust mechanism.

Abstract: A calcium fluoride crystal produced in accordance with a method for producing calcium fluoride crystal on the basis of refining a raw material of calcium fluoride and causing crystal growth of the refined calcium fluoride, the method including a process of raising a purity of the calcium fluoride to complement the refining, wherein a transition density in crystal is not greater than 1×105/cm2, and that dispersion of transition density inside an effective portion in crystal is in a range of ±5×104/cm2. Also disclosed is an optical element to be manufactured by use of such CaF2 crystal.

Abstract: A diffraction optical element comprises a substrate, a diffraction grating formed on the substrate with a material with low ultraviolet resistance and an ultraviolet screening means arranged on the substrate at a position closer to the incident light receiving side of the optical element relative to the diffraction grating. The ultraviolet screening means comprises a dielectric multilayer film and is formed on the other side of the substrate than the side carrying the diffraction grating. Alternatively, the ultraviolet screening means may be provided as a separate member from a diffraction optical element and arranged at a position closer to the incident light receiving side of the diffraction optical element in an optical system.

Abstract: A mold used for press-molding precision parts, such as an optical element formed of glass. A carbon film is formed at least on the molding surface of a matrix of the mold via an intermediate layer or without such a layer. The carbon film is shaped with a carbon ion beam having a desired ion energy such that a plurality of projections having an average height of from 0.5 to 30 nm are arranged at an average pitch of from 5 to 30 nm. Such a shape of the carbon film decreases the surface energy and frictional coefficient of the film and increases adhesion strength of the film to the matrix without impairing the surface roughness of an optical element to be molded. Thus, a resultant mirror surface of the mold is highly durable, free from film peeling and cracks in the formation of glass.

Abstract: An optical low-pass filter includes an optical member formed of a material capable of absorbing light in a particular wavelength range, e.g., an infrared range. The optical member has a plurality of ridge-like portions formed on at least one surface thereof at a predetermined pitch. The ridge-like portions comprise a phase type diffraction grating which has a low-pass filtering effect with respect to bundles of optical transmission rays passing therethrough.

Abstract: A roll-shaped mold for forming an information recording medium has a pattern forming layer formed into a film on a roll-shaped mold substrate and having a pattern for formation of a groove for a track on a resin substrate for the information recording medium by heat molding on the circumferential wall of the pattern forming layer.

Abstract: The present invention relates to a glass blank for producing optical element used for the press molding thereof, having a core glass and a surface layer covering at least the optically functional surface of the core glass. The surface layer consists of an evaporation glass. This invention also relates to the technique to mold a glass lens using the glass blank.

Abstract: Disclosed is a glass blank used in a producing process for molding an optical element by heating a glass material and press molding the glass material in a mold having optical functional surfaces. Employed is the glass blank having the glass surface coated with a reaction preventive layer and a hydrocarbon layer or with the hydrocarbon layer.

Abstract: In a process for manufacturing an optical element, in which a molding material is put in molds and is heated and press-molded to manufacture an optical element, a preheating treatment of the molding material is performed before it is put in the molds at a reduced pressure and a temperature lower than a temperature during the press molding.

Abstract: In a method of molding an optical device by press-molding a glass preform by using molding dies, the press-molding process is executed under a mixed gas atmosphere of a nonoxidizer gas and a hydrocarbon gas.

Abstract: An infrared reflection-preventing film including a titanium oxide layer disposed on an infrared optical substrate and a film of at least one second layer laid further on said first layer.