Canon Kabushiki Kaisha

Tetsuo Kuwabara

Kiyoshi Yamamoto

Masaaki Yokota

Kazuo Fujibayashi

Osamu Takamatsu

Akihiko Shiraishi

Yasushi Taniguchi

Masaaki Nakabayashi

Fumitaka Yoshimura

Isamu Shigyo

Masaki Ohmori

Nobukazu Yogo

Sunao Miyazaki

Shuji Murakami

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&#xd7;10/cm, and that dispersion of transition density inside an effective portion in crystal is in a range of &#xb1;5&#xd7;10/cm. Also disclosed is an optical element to be manufactured by use of such CaF2 crystal.

Calcium fluoride crystal and method and apparatus for using the same

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.

Diffraction optical element, optical system and optical device

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.

Mold and method of manufacturing the same

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.

Integral infrared absorbing optical low-pass filter

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.

Roll-shaped mold for information recording medium

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.

Molding method using glass blank

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.

Optical element and glass blank for producing the optical element

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.

Process for manufacturing optical element

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.

Growing community of inventors

Urawa, Japan

Tetsuo Kuwabara