Abstract: This linear motion rolling guide unit is provided with a seal structure capable of being applied to an existing linear motion rolling guide unit without changing the basic specifications thereof. A positioning pin-carrying mounting plate is fixed to a slider. Each of seal members incorporated in the seal structure comprises an upper seal portion and side seal portions. The positioning pins provided on the mounting plate are inserted into positioning pin holes of the seal members, whereby the seal members are positioned, the seal members being then fixed to the mounting plate by fixing screws inserted thereinto from the outer side of a scraper plate provided in contact with the seal members. The seal members of the seal structure are renewed by removing the same by outstretching the side seal portions thereof around the central parts of the upper seal portions thereof, and installing new seal members.

Abstract: A method for producing an oxide glass thin film is provided, in which volatilization of additives in a porous film from which the thin film is formed is effectively suppressed, and which the oxide glass film has a desired arrangement of refractive index with a low optical loss. According to this method, glass fine particles mainly containing SiO.sub.2 with a first additive are deposited on a substrate to form a porous thin film. A gas containing a second additive is supplied to a first chamber and heated to a first predetermined temperature profile to provide a heated gas containing an oxide. After disposing the substrate in a second chamber communicated with the first chamber, the substrate is heated to make the deposited porous glass into transparent glass while controlling a temperature in the second chamber according to a second temperature profile.

Abstract: The linear motion rolling guide unit has sealing devices that can be applied without having to modify the fundamental specifications of the existing unit and which can also be installed and removed easily. Each of the seals in the sealing device comprises a metal plate core and a rubber bonded to the core by baking. The core has at the central part a notched portion that allows a pair of seal side portions to be opened or expanded. Replacement of the seals can be done simply by fitting new seals over the track rail from above. The interference of the seals in the assembled sealing device can be adjusted easily by adjusting the distance that the adjust screws, whose front ends contact the side surface of the core, are screwed in.

Abstract: A method of producing an oxide glass thin film includes a process to obtain a transparent glass film, in which volatilization of additives in a porous film deposited is effectively suppressed and which can provide an oxide glass thin film having a desired arrangement of refractive index with a low optical loss. The method is for producing an oxide glass thin film, in which glass fine particles mainly containing SiO.sub.2 with additives are deposited on a substrate to form a porous thin film and then heated to form a transparent glass film. In the method, vapor of oxides of additive components is mixed in an atmosphere in which the porous thin film is heated to form the transparent glass film, whereby stopping the volatilization of the additives in the porous film deposited, preventing diffusion of the additives added to a core layer, and preventing the volatilization of glass transition temperature lowering components of additives (P.sub.2 O.sub.5, B.sub.2 O.sub.3, GeO.sub.2, etc.).

Abstract: A heating furnace for heating a porous preform made of fine particles of highly pure quartz glass for an optical fiber, which furnace comprises a cylindrical furnace body, a heater installed in said furnace body and a muffle tube installed inside said heater to separate a heating atmosphere from said heater, wherein said muffle tube is made of highly pure carbon and coated with a gas impermeable carbon, which furnace prevents contamination of the preform with impurities and has long life.

Abstract: There is provided a heating furnace comprising a furnace body, a cylindrical zone heater in the furnace body, a muffle tube installed through the furnace body for thermally treating a porous preform made of high purity quartz glass by moving the preform vertically therethrough and a partition means in the portion of the muffle tube projecting above the furnace body to divide an interior space of the muffle tube into an upper space and a lower one.