Abstract: A method and system are described 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 vapors are delivered in a vapor stream entrained with the carrier gas. In general, the present invention involves utilizing the pressure of the vapor leaving the bubbler as the specific characteristic monitored and controlled to ensure that the concentration level of carrier gas to vapor is maintained at the desired level throughout the manufacturing process.The present invention involves introducing a concentration detector within the flow path of the bubbler vapors from the bubbler and having the output of the concentration detector input to a concentration controller. The concentration controller compares the concentration value received from the concentration detector to a desired concentration value determined for the system.

Abstract: An apparatus is provided comprising means for creating substantially the same or mirror image first and a second gas flow patterns near the surface of first and second transducers. The means include an inlet conduit, an inlet port, a main conduit device, and an output port. A device is also provided for causing the first transducer to send a signal to the second transducer and for measuring the time taken for the signal to travel from first transducer to the second transducer. The inlet port is coupled to the inlet conduit, preferably centrally, and the output port is coupled to the main conduit device. The inlet conduit is comprised of a first branch and a second branch. Both branches have first and second ends, the second end of the first branch being coupled to the main conduit device at a first location, and the second end of the second branch being coupled to the main conduit device at a second location.

Abstract: An optical fiber formed from a glass preform substantially free of OH impurities is disclosed. The optical fiber is made to be free of OH impurities by a method having the steps of introducing a moving stream of vapor mixture including at least one compound glass-forming precursor together with an oxidizing medium into a tube, while generating a hydrogen-fee 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 glass preform is drawn to produce the optical fiber.