Abstract: In accordance with the invention, a plurality of elongated refractory bodies are laminated together by placing the bodies in close adjacency, exposing the adjacent bodies to a plasma torch heat source, and moving the bodies longitudinal past the torch at a nonzero average rate which includes a reciprocating (e.g., oscillatory) component to longitudinally spread the zone of heating. Where the bodies are a rod to be laminated within a hollow tube, it is advantageous to reduce the air pressure between the rod and tube, thereby eliminating potential contaminants and, at the same time, biasing the tube to collapse against the rod. This method is particularly useful in laminating overcladding tubes to core rods to form optical fiber preforms.

Abstract: Sol-gel processing of a silica glass body is facilitated by rapid drying. The body, having been heated to a temperature of about 200.degree. C. in a hermetically sealed vessel, is vented while reducing temperature. Termination of drying coincides with reduction to atmospheric pressure.

Abstract: Heating a wet colloidal gel body in an autoclave above its 1-atmosphere boiling point, under rigorously defined conditions, avoids shrinkage during subsequent drying. As a consequence, drying rates may be increased, and handling care becomes less critical.

Abstract: Bent sol-gel produced tubing is straightened by drawing, with tensile force and operating temperature to result in minimal plastic flow, so that size reduction is small. The method is usefully applied to reject recovery in the preparation of overclad tubes, which as encompassing closely-fitting core rods, form the composite preform from which optical fiber is drawn.

Abstract: An induction furnace for reflowing a portion of an optical preform in order to draw a lightguide fiber therefrom. The furnace has an axially located tubular iridium susceptor which is centrally disposed within a beaker and a sleeve is positioned concentrically around the susceptor. The sleeve is surrounded by an insulating grain. A high frequency coil is energized to couple its electromagnetic field to the iridium susceptor to heat and reflow a portion of the preform in order to draw the fiber therefrom. The furnace housing is sealed to provide an inert, non-oxidizing atmosphere for the iridium susceptor.

Abstract: A convenient method of producing porous silica particles is disclosed. The particles produced by the method can have impurity levels in the parts-per-billion range, and can have substantially uniform size. The particles are advantageously used to produce silica-containing glass bodies such as optical fiber preforms, silica tubes, lenses, rods and the like. The method comprises forming a silica-containing sol in comminution device or forming such a sol and introducing it into a comminution device, causing a gel to form from the sol, and comminuting the gel in the comminution device such that substantially dry, porous particles result.

Abstract: The transverse cross section of a body is modified by the steps of: a) determining the extent to which the body has material in excess of a desired shape at a plurality of points, b) exposing the body to a local heat source having a temperature sufficiently high to remove material from the surface of the body, and c) moving the surface of the body in relation to the source at a speed which decreases in regions where the body has material in excess of the desired shape so as to remove more material from such regions than from other regions. In a preferred embodiment, the body is an optical fiber preform, the local heat source is the fireball of a plasma torch, and the body is moved relative to the torch by rotating the preform at a controllable angular velocity while the torch is translated along the length of the preform.

Abstract: 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.

Abstract: A new method for fabricating devices which include multicomponent metal halide glasses, e.g., multicomponent metal halide glass optical fibers, is disclosed. In accordance with the inventive method, a multicomponent metal halide glass body, essentially free of crystallites, is produced by cooling essentially every portion of a melt incorporated into the glass body at a quench rate which is necessarily greater than or equal to about 10 Kelvins per second (K/sec). This necessary quench rate is achieved by successively quenching relatively small portions of the melt, e.g., thin layers or droplets of melt material, having relatively small cross-sectional dimensions.

Abstract: A method for forming articles which include silica-containing glass bodies, as well as the resulting articles, are disclosed. In accordance with the method, silica-containing gel particles are fused to form a glass body. In contrast to previous such methods, these particles are formed by mechanically, substantially uniformly subdividing either a substantially cohesive gel body, or an ungelled or partially gelled sol capable of yielding a substantially cohesive gel body, to form substantially uniformly sized, wet gel particles. Significantly, only substantially cohesive gel bodies which are also substantially elastic are useful in the invention, i.e., mechanical subdivision of non-elastic gel bodies results in these bodies undergoing plastic flow to yield non-particulate, pasty masses.

Abstract: The disclosed simple, economical and rapid sol-gel process for forming a silica-based glass body, termed the "vapogel" process, comprises introduction of a silicon halide-containing gas (e.g., SiCl.sub.4 +O.sub.2) into an aqueous medium. The thus formed sol can gel within minutes, resulting in a monolithic gel from which particles having a narrow size distribution can easily be formed. The thus formed particles can be used to produce a glass body such as an optical fiber. Various techniques for forming the glass body from the gel are disclosed. Among the many advantages of the vapogel method are its ability to produce very homogeneous mixed oxide glasses of composition not obtainable by prior art sol-gel processes, and the advantageous mechanical properties of the gel produced by the method. The latter makes possible, inter alia, formation of particles having a relatively narrow size distribution.

Abstract: Disclosed is BeF.sub.2 -based optical fiber. Such fiber can have, in addition to low loss, other advantageous properties. For instance, BeF.sub.2 -based dispersion shifted single mode fiber can have lower core-cladding index difference and larger core diameter than the corresponding SiO.sub.2 -based fiber, and BeF.sub.2 -based graded index multimode fiber can have larger bandwidth than the corresponding SiO.sub.2 -based fiber. The inventive fibers have a core and a cladding containing at least 30 mol % BeF.sub.2, and may contain up to 40 mol % of AlF.sub.3, and one or more members of the group consisting of NaF, KF, MgF.sub.2, CaF.sub.2, PbF.sub.2, PF.sub.5, and SiF.sub.4. An exemplary and currently preferred glass has nominal composition (in mol percent) 30KF-(15-x)CaF.sub.2 -xPbF.sub.2 -10AlF.sub.3 -45BeF.sub.2, with x.ltoreq.15. Single mode fibers according to the invention have minimum total dispersion in the range 1.5-2.0 .mu.m, and typically have 0.25%.ltoreq..DELTA..sub.esi .ltoreq.0.6%, and 2.5 .mu.m.

Abstract: A fast food serving tray has the shape of a ship or boat. It is formed from a partly assembled, knocked down structure formed from an integral, single blank of cardboard or the like. The pre-assembled arrangement has the sides of the boat structure flat and co-planar with each other. The side walls are preferably adhesively secured to each other at each end of the tray. When the side walls are spread apart to form the rounded shape of a ship bowl, a folded bottom wall is brought into a planar relationship forming a reinforcement at the bottom edges of the side walls. Two generally circular openings are formed on top of the tray together with a relatively large rectangular central opening which is reinforced by a pair of inwardly turned rectangular panels, one at each side of the tray. The advance in the art is in an improved sturdiness and an ease of assembly.

Abstract: A fast food serving tray having the shape of a ship or boat is formed from a rectangular cardboard blank by bending the blank along its longitudinal axis and adhesively securing connecting tabs at the ends of the tray to each other. The invention reduces the cost of production of the blank and facilitates the assembly of the tray at the time of serving the food.

Abstract: Optical components using a germania-silica glass are made by a gel technique. Tetra pentyloxygermane and a silicon alkoxide are hydrolyzed to form a gel, which is subsequently dried. Optical components, including optical fibers and devices, can be made using glass prepared by this technique.

Abstract: Aluminum metaphosphate optical fibers are disclosed. In a specific embodiment, aluminum metaphosphate, doped with from 10 to 30 mole percent of diboron trioxide, is found to yield an optical fiber which combines the desirable properties of both high numerical aperture and low material dispersion. The fiber is nonhygroscopic and has a high melting temperature. The index of refraction of the glass may be lowered by doping with silicon dioxide. Consequently, a graded fiber may be made by increasing the concentration of silicon oxide from the core to the cladding.

Abstract: Optical fiber preforms are produced by means of a duplex hot zone, a section of which is defined by an r.f. generated plasma fire ball. The process operates within a tube with gaseous precursor material reacting within the hot zone to result in deposited material of the desired preform glass composition. A "smoothing" region within the hot zone is defined by tube surface at a temperature sufficiently elevated to consolidate any particulate material resulting from reaction. In some aspects, the disclosed procedures may be regarded as Modified Chemical Vapor Deposition. Commercial significance resides in significantly increased throughput of preforms and, consequently, in fiber.

Abstract: Aluminum metaphosphate optical fibers are disclosed. In a specific embodiment, aluminum metaphosphate, doped with from 10 to 30 mole percent of diboron trioxide, is found to yield an optical fiber which combines the desirable properties of both high numerical aperture and low material dispersion. The fiber is nonhygroscopic and has a high melting temperature. The index of refraction of the glass may be lowered by doping with silicon dioxide. Consequently, a graded fiber may be made by increasing the concentration of silicon oxide from the core to the cladding.

Abstract: A ceramic composition and processing procedure is described which is useful in electric and electronic devices such as thermistors. The ceramic composition, which may be described as a semiconducting barium titanate, exhibits a large positive temperature coefficient of resistance. Advantages are ease and convenience of fabrication with lower sintering temperature than conventional processing and use of an air atmosphere instead of nitrogen or oxygen atmospheres. This facilitates batch processing and permits convenient sintering in a continuous kiln.