Mitsubishi Cable Industries, Ltd.

Shin-etsu Chemical Co., Ltd.

Mitsubishi Jukogyo Kabushiki Kaisha

Dainichi-nippon Cables, Ltd.

Koichi Suzuki

Takeshi Satake

Hiroyuki Hayami

Masatoshi Takita

Isao Shirasu

Masayoshi Hachiwaka

Takeji Akutsu

Tokuji Hayashi

Yoshimasa Tsukamoto

Masakatsu Kimura

Seiroku Oose

Yasutaka Hirao

Yuzo So

A silica glass optical fiber superior in resistance to ultraviolet rays, which fiber comprises a doped silica glass cladding layer formed on a silica glass core, said silica glass core having an OH content of 10-1000 ppm, a fluorine content of 50-5000 ppm, and being substantially free of chlorine.

Ultraviolet resistant silica glass fiber

The present invention provides an optical energy beam transmission path structure comprising at least one pair of optical fibers each having a connection end, and at least one fiber connector for connecting the connection ends of the paired fibers substantially coaxially. A small axial air gap is formed between the connection ends of the paired fibers, and an annular clearance is formed immediately around the connection end of the glass body of each fiber.

Optical energy beam transmission path structure

This invention is directed to a high temperature resistant lighting device for lighting the interior of a high temperature furnace for observing the furnace interior from the outside. A lighting lamp (5) and an inspection device (9) are housed within a metallic heat protective casing (10) having a cooling path (27) for circulation of cooling water. The lamp and an objective section (91) of the inspection device are rotatable with its associated drives (53) and (97) so that the illuminating direction of light from the lamp and the viewing direction of the objective section are variable so as to direct illuminating light beams from the lamp toward a wall surface of the furnace via a viewing window (4) and focus reflected light beams from the wall surface of the furnace onto the objective section. The light beams focused on the objective section are led out of the furnace through an optical fiber bundle or cable (92) and picked up to form a video image of the wall surface of the furnace by means of a TV camera (17). Accurate and scrupulous observation of the inner wall surface of the furnace is made possible by varying the directions of the lamp and the objective section.

High temperature resistant lighting device

Growing community of inventors

Suita, Japan

Koichi Suzuki