摘要:
A method for making a glass preform substantially free of OH impurities is disclosed. The method comprises the steps of introducing a moving stream of a vapor mixture including at least one compound glass-forming precursor together with an oxidizing medium into a tube, while generating a hydrogen-free isothermal plasma on an outer surface of the tube to react the mixture and produce a glassy deposit on an inner surface of the tube. The method uses a plasma torch or a radio frequency furnace.
摘要:
A device (80) for sealing a furnace (50) which is used to draw a fiber (52) from a rod-like preform (51) includes a housing (82) having a cavity (121) for receiving a disc (111). The disc (111) is suspended for movement in the cavity in a plane lateral to the preform that extends through a center opening (116) in the disc and into the furnace. An inert gas is supplied to the cavity and directed inwardly through radially disposed passageways (118--118) in the disc (111) to impinge on the preform and split into two streams which move along the preform in opposite directions to prevent the entry of ambient air into, as well as the escape of gas from within, the furnace. The inert gas also causes the disc to be moved within the cavity to compensate for irregularities in the preform or for its misalignment from a vertical axis of the furnace, and provides a cushion so that contact between the disc and the preform is avoided.
摘要:
A sealed rotary joint and method are described wherein a purge fluid is passed over a tube rotating within an end cap and through a ball bearing component of the joint.
摘要:
A sealed rotary joint and method are described wherein a purge fluid is passed over a tube rotating within an end cap and through a ball bearing component of the joint. A vapor stream including a vaporized glass forming precursor entrained in an oxidizing carrier gas is passed into a rotating optical fiber preform tube through a housing supporting the ball bearing. A stream of the oxidizing carrier gas at a pressure greater than the pressure of the vapor stream can act as the purge fluid.
摘要:
To attain high strength optical glass fibers, the glass preforms, from which the fibers are drawn, must generally be free of surface imperfections such as bubbles, and air lines. It has been discovered that these imperfections can be removed quickly and cleanly by contacting the preform surface with a substantial portion of the electrically conducting plasma region (the plasma fireball) extending from a plasma torch. Significantly, the surface material is substantially removed by vaporization, due to the extremely high plasma temperature (>9000.degree. C. at the plasma center) of the isothermal plasma torch. Though the temperatures in the tail of the plasma fireball are substantially less than at the plasma center, the temperatures are generally still several thousand degrees centigrade. These tail temperatures typically are sufficiently high to cause vaporization of most refractory dielectrics making the inventive method applicable to the fabrication of a wide variety of articles comprising refractory dielectric bodies.Advantageously, selective etching, according to one aspect of the inventive method, is used to remove fiber preform eccentricity and to fabricate optical fiber preforms with non-circular cross-sections for such applications as fiber sensors. Selective etching can result by controlling the plasma fireball location, the rotation of the silica preform, and/or the travel of the fireball across the preform. Significantly, the fireball location is controlled, among other ways, by injecting into the torch an additional gas that has a high ionization threshold or by inserting a probe along the axis of the torch. In either case, a substantial portion of the plasma fireball is advantageously "pushed" outside the torch for ease of contact with the silica preform surface, or any other refractory dielectric being processed.
摘要:
Apparatus for supplying fluid to a rotary tube uncontaminated with ambient air comprises an end cap having an open ended bore in which an end portion of the tube may be rotatably positioned, a first conduit extending into the end cap through which fluid may be fed into the rotary tube, and a second conduit communicating with the end cap bore through which a purge fluid may be fed into and at least partially through the bore to the exterior of the end cap.
摘要:
A method is disclosed for controlling the delivery of vapor from a bubbler containing a supply of liquid through which a carrier gas is bubbled and from which bubbler vapor is delivered in a vapor stream entrained with the carrier gas. The method comprises the steps of sensing the ratio of vapor to carrier gas in the vapor stream and applying heat to the liquid within the bubbler at rates relative to the sensed ratios of vapor to carrier gas being delivered from the bubbler in a vapor stream to hold the ratio constant.A vapor delivery control system is also disclosed which comprises a vaporizer, a heater thermally coupled with the vaporizer, and means for maintaining a supply of liquid in the vaporizer. The system further includes means for introducing a carrier gas into the vaporizer, means for conducting the carrier gas and vapors of the liquid entrained with the carrier gas from the vaporizer, means for sensing the ratio of vapor to carrier gas being conducted from the vaporizer, and means for controlling the heater responsive to the ratio of vapor to carrier gas sensed by the sensing means to hold the ratio constant.
摘要:
A vapor delivery system is disclosed comprising a bubbler 12 is adapted to generate and deliver vapors from a vaporizable liquid contained therein, and a reservoir 30 in fluid communication with the bubbler 12 from which liquid may be continuously fed into the bubbler to replenish liquid vaporized within and withdrawn from the bubbler. The system further comprises means for sensing the level of vaporizable liquid in the bubbler and means for providing a gaseous head pressure in the reservoir of variable magnitude dependent upon the level of vaporizable liquid sensed by the sensing means to maintain the level of liquid in the bubbler substantially constant.
摘要:
A torch and mount assembly wherein the torch, which has a plurality of gas receiving nipples is carried in a housing through which it extends. The housing has a plurality of walls forming a substantially air tight enclosure. In at least one wall of the housing are one or more leakproof fittings which are connected to similar leakproof fittings for the nipples by means of preferably flexible gas conduits within the housing. In the system, gaseous mixtures are applied from a source or sources to the fittings in the housing wall remote from the high temperatures of the torch, while the conduits within the housing are protected from mechanical and thermal stresses. An inert gas from a suitable source is introduced under pressure into the interior of the housing to reduce leakage from the torch into the housing. The atmosphere within the housing is heated, and the constituents of the housing atmosphere are monitored to aid in detecting leakage.
摘要:
A vapor delivery system for the manufacture of an optical preform includes a deposition bubbler (60) and another bubbler (40) referred to as a supply bubbler which is interposed between a reservoir (24) of a liquid and the deposition bubbler. Heat energy is applied to the supply bubbler and to the deposition bubbler to vaporize liquid therein. A carrier gas is introduced into the liquid in the supply bubbler at a location below the free surface and into the deposition bubbler to cause vapor of the liquid to become entrained in the carrier gas and to flow from the supply bubbler into the deposition bubbler and from the deposition bubbler to a substrate tube from which an optical preform is made. Facilities are provided for maintaining sufficient liquid in the supply bubbler and suitable temperatures of the liquid in the supply and deposition bubblers to control the vapor flow into and out of the deposition bubbler to prevent unintended perturbations in the deposition bubbler. As a result, the concentration level of the vapor which is entrained in the carrier gas and delivered to the substrate tube is maintained at a substantially constant value.