Abstract: A granular body, from which an article having a nonuniform refractive index may be formed, has grains of two substances which have different refractive indicies in a geometric distribution in the granular body corresponding to the geometric distribution of the substances required for the nonuniform refractive index of the article and a way of shape-stabilizing the granular body. A method of making the granular body comprises controllably feeding the grains into the geometric distribution in the granular body and shape-stabilizing it. Preferably the granular body is compressed into a porous compact which holds itself together and is treated with a gas to achieve desired optic properties in the article.

Abstract: An infrared radiator includes a non-circular jacket tube made of quartz material, which may be quartz glass, the length of which is a multiple of the larger interior diameter and the interior of whch, in a sectional view, is separated into two areas, in each of which a heating wire extends in the direction of the tube axis. The heating wires are electrically conductive and connected to each other at one end of the jacket tube and lead to the exterior via connecting pieces at the other end. Two cross pieces which protrude from the inside wall of the jacket tube face each other and are directed toward the direction of the axis of the jacket tube so as to form the two areas.

Abstract: Continuous ovens are known including heat radiators, especially electrical infrared radiators for the thermal treatment of thin, plate-like components, especially printed circuit boards fitted with electronic components, including a conveying device which has two spaced-apart, parallel, synchronously driven continuous drive bands each having support elements for the plate-like components. In order to make a continuous oven including a conveying device wherein the printed circuit boards to be soldered are carried through the oven on a defined plane in their entire structural length such that the structural changes involved do not strongly affect the thermal conditions in the oven, an auxiliary drive band is disposed between the two drive bands and parallel thereto.

Abstract: A vertical drying chamber, for the continuous drying of finely divided solids at temperatures in the range of 800.degree. to 1000.degree. C. by the evaporation of moisture adhering thereto, is formed by the interstice between an inner tube and an outer tube. The outer tube is surrounded by a heat source (electrical resistance heating, infrared radiator) and is composed of a plurality of tube sections plugged one into the other, each tube having a funnel-shaped upper end into which the bottom, plain end of the tube section above it extends. Between the interconnected tube ends spacers are provided. The tube sections are made of a material that is permeable to infrared radiation.

Abstract: Radiant units are known in the form of a plate-like assembly having a supporting frame which accommodates a plurality of radiant lamps on holders, the radiant lamps being shielded by a front cover and a back cover, the front cover, which is permeable to radiation, being held removably. To design a radiant unit so as to permit easy and rapid installation as well as the quick replacement of the front cover as well as of the rear cover in order to change the internally mounted radiator, and also to permit compensation for different thermal expansion between the covers and the supporting frame, the front and/or rear cover are held with their outer faces against abutments joined to the supporting frame, and spring-loaded clamps are associated with the inner faces and urge the cover from the inside against the abutments.

Abstract: Granular silicon dioxide is placed in a treatment chamber which is heated to a temperature ranging from 700.degree. to 1300.degree. C. The chamber is then rotated for a prescribed period of time to mix the grains while a gaseous atmosphere of chlorine and/or hydrogen chloride is passed through the treatment chamber. The mixing period is followed by a resting period which is at least ten times longer than the mixing time. During the resting period the grains are exposed to a constant electric field having a strength of 600 to 1350 V/cm applied across the chamber. The foregoing cycle is repeated several times. For working the process a device is used which includes a quartz glass rotary tube into which hollow silicon carbide electrodes extend.

Abstract: A transmission line for optical radiation is disclosed, which has at least one optical fiber with core and cladding. The core consists of vitreous synthetic silicon dioxide, and the cladding of bitreous synthetic silicon dioxide doped with boric oxide and/or fluorine. The fiber is cooled over substantially its entire length to a temperature below 220 K. for the transmission of optical radiation in the wavelength range from 160 to 300 nm. Such transmission lines are used in spectroscopy, in machining processes, in medicine and chemical processes, and for biological purposes.

Abstract: Continuous ovens are known for soldering electronic components on circuit boards, with a conveyor belt having supports for the circuit boards, and having infrared radiators disposed in a spaced-apart relationship along the conveyor belt above and/or below the plane of belt movement, which are associated with at least one preheating zone and, following this zone in the direction of movement of the belt, with a soldering zone. To develop a continuous oven such that the temperatures between large and small components to be soldered on circuit board will be nearer one another in the soldering zone than in conventional ovens, a cooling zone is disposed between the preheating zone and the soldering zone, in which a forced cooling is performed with a gaseous coolant which is driven by a blower through nozzles disposed in the cooling zone substantially perpendicularly to the plane of the conveyor belt.

Abstract: A method of manufacturing a blank for a light-weight mirror. Graphite molding bodies are positioned at regular intervals on a base that functions as a mirror plate or backing plate. The base is surrounded up to the top of the molding bodies with a graphite wall. The interstices between the molding bodies and between the wall and the molding bodies are filled with granular quartz. The assembly is heated in an evacuated furnace to approximately 1730.degree. C. into a honeycomb-shaped supporting structure that is securely fastened to the base. The graphite molding bodies and wall are removed after cooling. Either a backing plate or a mirror plate in the form of another plate is applied to the resulting supporting structure.

Abstract: A method of vitrifying a porous cylindrical article made out of glass soot, especially for manufacturing a preliminary blank for optical fibers. The article is heat-treated in a furnace in a vacuum or in an atmosphere that contains helium. The porous article is placed in a horizontal graphite tube in the furnace, is sintered therein for 20 to 40 minutes in a vacuum or in a helium atmosphere with reduced pressure at 1250.degree. to 1400.degree. C., and is subsequently vitrified by heat-treating the sintered article at first in the sintering atmosphere, while slowly rotating it in the hot graphite tube for 20 to 40 minutes at approximately 1450.degree. to 1600.degree. C. and then while rotating it in the graphite tube more rapidly than in the first stage for 10 to 30 minutes at approximately 1650.degree. to 1750.degree. C.

Abstract: In the production of an article of extremely pure synthetic silicon dioxide, wherein silicon tetrachloride is mixed with water to effect hydrolysis, the resulting hydrolysis product is dried, and the resulting dried particulate product is further processed into the desired article, the improvement which comprises employing a ratio of silicon tetrachloride to water so that the hydrolysis product is in the form of a gel, distilling by-product hydrochloric acid out of the gel, preliminarily drying the gel at 100.degree. to 1000.degree. C. to produce an initial product, milling the initial product into a fine granulate at room temperature, separating from the milled granulate a fraction with a particle size of about 40 to 1000 .mu.m, and drying the screened-out granulate fraction while slowly heating to no more than 1400.degree. C. to form the resulting dried particulate product that is further processed into the desired article. As a result, high quality bubble free articles are produced.

Abstract: An oven for the heat treatment of semiconductor substrates, especially a diffusion oven, having an upright, heatable quartz tube and a support system made of up rods or tubes into which one or more diffusion racks can be inserted which accommodate the wafer-like substrates separated from one another and substantially parallel to one another. To create a vertically operated oven having a rheologically efficient construction in which the support system for holding the diffusion racks will be highly variable, the support system has at least two vertical supports arranged parallel to one another, on which at least one rack rest 9 is disposed, on which rack rest the diffusion rack is placed such that the substrate wafers 8 stand substantially on edge during the treatment.

Abstract: A double-walled quartz-glass tube for semiconductor-technology processes. The overall structure comprises an inner tube surrounded by a coaxially positioned outer tube. An annular space is left between them. The ends of the tubes that face in the same direction each have a closure. A processing-gas supply connection is mounted on the inner-tube closure and extends tight through the outer-tube closure. The outer tube is sealed tight at the other end against the outside of the inner tube. The outer tube has connections for supplying and removing a scrubbing gas. The object is to prevent the occurrence of defects due to differences in the extent that the two tubes expand to as the result of the heat generated during processing. The inner tube has a diameter of at least 150 mm. At least one of the closures is essentially flat. The axis of the processing-gas supply connection is in alignment with the axis of the inner tube.

Abstract: Disclosed is a method for the axial building up, in a vertical arrangement, of a hollow cylindrical soot body having no internal support and consisting substantially of silicon dioxide by means of at least one flame hydrolysis build-up burner serving for the soot production. In this method the soot is deposited at the beginning of the build-up onto an auxiliary body, and during the build-up the build-up burner and the growing soot body are rotated relative to one another, and the burner is at the same time held at an unvarying distance from the growing end of the hollow cylinder and centrally above the predetermined cross section of the upwardly growing end of the cylinder wall. The penetration of soot into the interior of the cylinder is prevented by means of a directed gas stream.

Abstract: An apparatus for loading a furnace with semiconductor wafers is known, which has at least two heat treatment chambers (1A, 1B, 1C, 1D), each of them having an associated stationary loading unit (8) with a receptacle movable in the direction of the furnace axis via a feed apparatus and having a loading system (2A, 2B, 2C, 2D) for semiconductor wafers. In order to provide such an apparatus for automatically loading the furnace with semiconductors which facilitates loading and overcomes the disadvantages of the known apparatuses, the apparatus according to the invention has a common central loading station (9) for all the semiconductor loading systems (2), and these loading systems are removable from the loading unit (8).

Abstract: A method of manufacturing practically stria-free, bubble-free, and homogeneous quartz-glass plates of any desired configuration and with a surface area that exceeds the cross-section of the full circular quartz-glass cylinder that is employed as a starting material. The cylinder is continuously lowered into a furnace shell flooded with an inert gas, in which it is heated to a flowing temperature in the range of 1700.degree. to 1900.degree. C. until some of the quartz-glass flows off into a graphite crucible. The crucible is preferably clad with zirconium-oxide.

Abstract: Disclosed is a self-contained radiant unit in the form of a portal for use particularly as a drying and baking tunnel for the automobile industry which is equipped with a plurality of infrared lamps on its inner surfaces. Air inlet openings are provided in the roof and/or side walls of the portal, at least over the region midway along with their horizontal extension, for the turbulence-free removal of the vapors emanating from the surface of the object being treated as well as of suspended particles present in the drying and baking zone.

Abstract: A rack for supporting wafers has a pair of parallel struts with kerfs therealong for supporting the wafers. A dummy wafer is attached to the struts near each end of the struts to connect the struts structurally as the rack and serve as rack-handling handles. The dummy wafers are parallel to the adjacent kerfs and thus the wafers therein and dimensioned similarly to the wafers for providing favorable gas and heat distribution when a wafer loaded rack is placed in a furnace. This adapts the rack for diffusion treatment of semiconductor wafers.

Abstract: A method of manufacturing practically stria-free, bubble-free, and homogeneous quartz-glass plates of any desired configuration and with a surface area that exceeds the cross-section of the full circular quartz-glass cylinder that is employed as a starting material. The cylinder is continuously lowered into a furnace shell flooded with an inert gas, in which it is heated to a flowing temperature in the range of 1700.degree. to 1900.degree. C. until some of the quartz-glass flows off into a graphite crucible. The crucible is preferably clad with zirconium-oxide.

Abstract: A tray made of silica glass or ceramic material with a seating component made out of U-shaped lengths, for disk-shaped elements and especially for round wafers, whereby the elements are secured in the seating component by means of slots. To provide a tray that is shaped in such a way as to provide easy access, is highly stable, and is designed to accept a wide range of wafer sizes, the seating component is in the form of two U sections, each with a base and two sides that are spaced by means of transverse tubes in such a way that the bases of the sections slope toward each other, the slots in the sides being deep enough for the upright elements to rest at points or along lines on the bases.