Fujikura Limited

Nippon Telegraph and Telephone Public Corporation

Doryokuro Kakunenryo Kaihatsu Jigyodan

Kansai Paint Company, Ltd.

The Fujikura Cable Works Limited

Matsuo Sangyo Co., Ltd.

Kabushiki Kaisha Toshiba

National Institute for Materials Science

Japan Atomic Energy Research Institute

Kazuo Sanada

Sadao Chigira

Osamu Fukuda

Takashi Tsumanuma

Tsutomu Maruyama

Koichi Inada

Shiro Takahashi

Atsushi Akiyama

Masanobu Hidaka

Kiyoshi Shimamura

Koji Suzuki

Fumiaki Komatsu

Naoki Shamoto

Yoshihisa Sawada

Villora Encarnacion Antonia Garcia

Katsuyuki Seto

Toshiyuki Tanaka

Kouji Tanaka

Hiroyasu Matsuki

Yasuyuki Sugawara

Toshiaki Kobayashi

Hiroshi Rindo

Koichiro Nakamoto

Yorihisa Sakaki

Naoshi Uesugi

Kuniaki Ara

Shotaro Hayashi

Tsunemi Kakuta

Kiyonori Ishii

Eiji Fukushima

Toshiaki Murayama

Tsugio Sonobe

The present invention provides a single crystal for an optical isolator having a Faraday rotation angle exceeding that of TGG single crystal in a wavelength region of 1064 nm or longer or in a wavelength region of shorter than 1064 nm, and is capable of realizing enlargement of crystal size, a production process thereof, an optical isolator, and an optical processor that uses the optical isolator. The single crystal according to the present invention is composed of a terbium aluminum garnet single crystal, and mainly a portion of the aluminum is replaced with lutetium.

Single crystal, production process of same, optical isolator, and optical processor using same

A method for reading of information, which comprises printing information on a metal substrate or a substrate capable of transmitting infrared rays of 2-10 .mu.m wavelength, with a marking ink containing tin oxide, indium-tin mixed oxide or a mixture of tin oxide or indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate, as necessary coating a clear coating or a coloring ink on at least the information-printed area of the substrate, and identifying the information by the use of a CCD camera sensitive to infrared rays of 2-10 .mu.m wavelength or an infrared detector. No noise is generated even when the reflectance of a light from the substrate surface is large, and the information can be identified (read) easily.

Method for reading of invisible marking

Information is printed on the surface of a substrate with a marking ink containing a mixture of an indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate, to prepare an invisible marking-printed material; and infrared rays of 2-10 .mu.m wavelength are applied onto the invisible marking-printed material to measure the infrared absorptivities of the invisible marking area and other area of said material and identify the information signified by the invisible marking.

Method for formation of invisible marking and method for reading of

A method of manufacturing a radiation-resistant optical fiber includes steps of a) heating a bare optical fiber to remove residual hydrogen gas present in the bare optical fiber and b) forming a coating layer consisting of a substance which does not allow permeation of hydrogen gas on the surface of the bare optical fiber from which the residual hydrogen gas has been removed.

Method of manufacturing radiation-resistant optical fiber

An image fiber preform for use in an image fiber according to the present invention includes a plurality of optical fiber strands, each optical fiber strand including a silica glass core which contains a dopant for increasing a refractive index of the core and a silica glass cladding surrounding the silica glass core, the silica glass cladding containing a fluorine dopant for decreasing a refractive index of the cladding, the cladding having an outer peripheral surface, and a quartz tube in which the optical fibers are closely arranged, wherein the cladding has a concentration of the fluorine dopant which decreases radially outward toward the outer peripheral surface of the cladding. in the present invention, an image fiber prepared from the image fiber preform and fabrication processes for the image fiber preform and the image fiber are provided.

Image fiber, image fiber preform, and manufacturing processes thereof

An image-transmitting fiber includes at least one first fiber element for transmitting light power therethrough, and a plurality of second fiber elements disposed around and extending along the first fiber element. The second fiber elements cooperates with one another for transmitting an image of an object therethrough. The first fiber element is greater in diameter than each of the second fiber elements.

Image-transmitting fiber

An optical fiber includes light-transmitting means comprising at least one optical fiber element, and a heat-resistant and radiation-resistant coating formed around the light-transmitting means. The coating comprises an inner buffer layer formed around the light-transmitting means and an outer layer of polyether ether ketone formed around the inner layer.

Heat and radiation resistant optical fiber

A fiberscope has a light source and a light guide for leading light emitted from the source onto an object disposed in liquid helium. A transmission system for transmitting the image of the object has an image guide. A body tube is fixed to one end of the image guide and faces the object. Objective lenses are disposed in the body tube to project the image of the object onto the one end face of the image guide. An eyepiece is fixed to the other end of the image guide, through which the image of the object is viewed. The interior of the body tube is kept under vacuum.

Very-low-temperature fiberscope

An optical fiber of a silica-based material includes a coating of cured silicone rubber covering an outer surface thereof. The cured silicone rubber coating, when subjected to an infrared spectroscopic measurement, has a transmissivity of not less than 70% at a wave number of 2100 to 2200 cm.sup.-1 at a coating thickness of 0.1 mm due to the infrared absorption due to the stretching and vibration of SiH. The coating of cured silicone rubber contains a neglibible amount of SiH so that the transmission loss of the optical fiber can be prevented from increasing over a long period of time.

Optical fiber

An apparatus for producing a multi-component glass fiber preform includes a multi-conduit burner 31 having five concentric conduits 31a-31e, the center three conduits (a), (b) and (c) being flush with each other at their ends, the fourth conduit d, interposed between the third (c) and outermost conduit (e) extends axially beyond the first three. The burner has a flange 33 to direct the flame onto a substrate. In operation glass raw material is fed through the inner-most conduit (a) by a carrier gas. The material emitted from conduits (a -d) is mixed in a mixing area 32. Glass raw material and a nebulized dopant salt solution are emitted and burned with hydrogen gas depositing particulate glass material or soot on an adjacent substrate to produce a multi-component glass fiber preform.

Apparatus for producing multi-component glass fiber preform

A method for producing a multi-component glass fiber preform which comprises the steps of nebulizing an aqueous solution of at least one metal salt, and reacting the nebulized solution and a gaseous glass raw material with oxygen gas at a high temperature to produce particulate glass material deposited on a substrate. Apparatus for producing such a preform is also disclosed.

Method for producing multi-component glass fiber preform

A microwave melter in which a material charged in a crucible is heated and melted by irradiation of microwaves, the melter including a melting furnace having an upper furnace body fixedly mounted on a support structure and a lower furnace body detachably connectable with the upper furnace body, a waveguide for guiding microwaves from a microwave generator toward the furnace, a crucible received rotatably and in a suspended state in the lower furnace body, and a feed pipe for feeding untreated material to the crucible.

Microwave melter

Growing community of inventors

Chiba, Japan

Kazuo Sanada