Abstract: Piston actuators and methods of its operation are described. The piston actuators include a housing defining a chamber having a piston therein and a spring seated against the piston to bias it into a starting position. The piston includes a ferromagnetic material, a magnet or both and a secondary magnet or ferromagnetic material, forming a first magnetic/ferromagnetic pair with the piston, is positioned to maintain the piston in a secondary position. A tertiary magnet or ferromagnetic material, forming a second magnetic/ferromagnetic pair with the piston, may assist the spring in maintaining the piston in the starting position. During operation, introduction into or removal from the chamber of an amount of fluid sufficient to overcome the force of the spring (and the tertiary magnet or ferromagnetic material) enables the attraction between the members of the first magnetic/ferromagnetic pair to move the piston to the secondary position as a snap movement.

Abstract: An I. S. Machine includes a blow station having a blow mold which closes to support a parison with the supported parison undergoing reheat and then being blown into a bottle. When reheat takes place air at low pressure is supplied to the blow tube to pressurize the interior of the parison to prevent the formation of a birdswing in a blown bottle. Air at a second pressure is supplied to the blow tube for blowing the parison into a bottle following reheat.

Abstract: An I.S. machine has a blow station where a parison is blown into a bottle. The parison is blown with a blow head at the “on” position on the blow mold and following the blowing of the parison, the blow head is lifted away from the blow mold. The spacing between the blow head and the mold is defined by a Pressure Profile which is responsive to the sensed pressure within the mold.

Abstract: An I.S. machine has a blow station where a parison is blown into a bottle. The parison is blown with a blow head at the “on” position on the blow mold and following the blowing of the parison, the blow head is lifted away from the blow mold. The spacing between the blow head and the mold is defined by a Pressure Profile which is responsive to the sensed pressure within the mold.

Abstract: A blowhead assembly for receipt over a parison finish to blow the parison within a blow mold and simultaneously cool the parison finish includes a blowhead body having a first chamber at one end for receipt over the finish of a parison in a blow mold, and at least one passage in the blowhead extending to the chamber from a first inlet for directing cooling air onto the external surface of a parison finish in the chamber. A second chamber in the blowhead body is spaced from the first chamber, and at least one second passage in the blowhead body extends to the second chamber from a second inlet for directing blow air into the second chamber. A first tube extends from the second chamber through the first chamber for receipt within a parison finish in the first chamber to feed blow air from the second chamber into the parison. A second tube extends from an exhaust passage in the blowhead body through the second chamber and through the first tube for receiving exhaust air from the parison.

Abstract: A blow mold assembly for an I.S. machine for blowing a parison of glass and cooling the blown parison into a formed bottle which can be removed from the blow mold. A blow head is lowered onto a blow mold and final air is applied. A predetermined time after the blow head engages the top surface of the blow mold the blow head is lifted a selected vertical distance above the top surface of the blow mold to an exhaust position allowing cooling air to escape from the blow mold. The selected vertical distance is selected so that at least a minimum pressure will continue within the formed bottle. The blow head is maintain at the exhaust position for a predetermined time and then retracted. The selected vertical distance and the predetermined time can be set as desired.

Abstract: The invention concerns an automated method for producing a blown glass body, in particular a glass wall of an electrochemical sensor, wherein an immersion tube (10), through which air or gas can flow, is immersed into molten glass an amount of molten glass from the molten glass mass, and wherein the (8) and subsequently withdrawn to remove removed glass is blown into the form of the glass body to be produced by means of the air or gas flowing through the immersion tube (10), comprising the following features:—the position of the surface (42) of the molten glass (8) in the adjustment direction of the immersion tube (10) is determined; an adjustment means (18) for the immersion tube (10) is controlled in correspondence with the determined position of the surface (42) such that the free end of the immersion tube is first immersed into the molten glass mass (8) up to a certain predetermined immersion depth (h) of molten glass; and then removed thereby retaining a predetermined amount—following removal from the mo

Abstract: An I.S. machine wherein a parison is blown into a bottle in a blow mold. The parison is initially suspended from the neck ring mechanism and the blow molds are displaced to close around the parison below the finish. The neck ring mechanism is displaced away from the mold and a blow head is located on top of the mold to provide final blow. A heat sensor senses when the parison, during reheat has reached the bottom of the mold and supplies a signal to a controller which starts final blow based on the time when this signal was supplied.

Abstract: A parison is blown in the blow mold of an I.S. machine and a control determines the time of the event by defining a local minimum in the pressure vs. time plot.

Abstract: A takeout for an I.S. machine includes a cooling tube which is displaceable between up and down positions. Displace is controlled to correspond to the desired heat removal along the path of displacement.

Abstract: A blow head mechanism for an I.S. machine wherein the blow head has a final blow tube. The final blow tube is supported for vertical displacement between an up position where the open end of the final blow tube is proximate the top of a blown parison and a down position where the open end of the final blow tube is proximate the bottom of a blown parison. The final blow tube is displaced at least once from the up position to the down position and back to the up position during the time when the blow head is “on” by a profiled actuator including a displacement profile which will displace the blow tube between the up position and a location where the upper neck portion meets the lower body portion at an average velocity higher than the average velocity at which the blow tube will be displaced between the location where the upper neck portion meets the lower body portion to the bottom of the blown parison.

Abstract: Production of a glass body provided with a glass membrane is disclosed, for a chemical sensor, in which a displaceably mounted dip tube through which a gaseous medium can flow is dipped into a mass of molten glass and pulled out again to withdraw a gob which is then put into the desired shape by supply of the gaseous medium. The dip tube is inserted into a mount, which is connected to a displaceably supported carriage which is then displaced as far as a lower end position (P1), which is defined on the basis of an adjustment device such that when the carriage moves downward the dip tube dips into the molten glass, and upon the retraction of the carriage the dip tube withdraws a gob that is suitable for processing. After one or more withdrawals of a gob, the one-piece or multiple-piece adjustment device is readjusted manually or automatically by a certain amount, to compensate for changes in the level of the molten glass caused by the withdrawal of gobs.

Abstract: The takeout has a cooling tube which oscillates within the bottle as the bottle is removed from the blow station of an I.S. machine and transferred to a deposit location.

Abstract: A takeout for an I.S. machine has a cooling tube which is displaceable between up and down positions. The open bottom of the cooling tube has an annular deflector which deflects some of the downwardly propelled cooling air radially outwardly from the cooling tube.

Abstract: A blow mold assembly for an I.S. machine for blowing a parison of glass and cooling the blown parison into a formed bottle which can be removed from the blow mold. A blow head is lowered onto a blow mold and final air is applied. The blow head is lifted a selected vertical distance above the top surface of the blow mold to an exhaust position allowing cooling air to escape from the blow mold. The selected vertical distance is selected so that at least a minimum pressure will continue within the formed bottle. The blow head is maintain at the exhaust position for a predetermined time and then retracted. A first pressure is applied while the blow head is at the lowered position and a higher pressure is applied while the blow head is at the escape position.

Abstract: The invention concerns an automated method for producing a blown glass body, in particular a glass wall of an electrochemical sensor, wherein an immersion tube (10), through which air or gas can flow, is immersed into molten glass (8) and subsequently withdrawn to remove an amount of molten glass from the molten glass mass, and wherein the removed glass is blown into the form of the glass body to be produced by means of the air or gas flowing through the immersion tube (10), comprising the following features:

Abstract: Apparatus for monitoring application of air through a dual-stage blowhead to blow mold a container includes a first solenoid valve for applying final blow air through the blowhead to a container in a mold and a second solenoid valve for applying finish cooling air through the blowhead around the finish of the container in the mold. Electronic circuitry is coupled to the first and second solenoid valves for detecting timing of application of first and second electrical valve control signals to the valves. Air pressure sensors are operatively coupled to the first and second solenoid valves for generating associated electrical signals indicative of timing of application of air by the first and second solenoid valves to the blowhead.

Abstract: Method of patterning or forming color gradients and/or designs on a glass surface are disclosed. Patterns are formed by depositing a film of metal on at least one surface of the glass; forming a layer of photoresist over the metal; exposing the article to light through a mask which contains a desired pattern; developing the piece to remove the exposed photoresist to reveal the underlying metal; removing the underlying metal to reveal the underlying glass; and removing the unexposed photoresist to reveal the underlying metal. To form color gradients or color patterns, the glass article is further treated in hydrogen at a temperature in the range of 300-600.degree. C. to effect the desired surface coloration.

Abstract: This invention provides a contamination-resistant float glass showing even quality in durability and its good quality sufficienty. The film for contamination-resistance is formed only on the top-side surface of a float glass. The surface, free from tin diffused from a float bath, can be identified by ultraviolet irradation. A solution including a chemical adsorbent like fluoroalkyltrichlorosilane is applied to the top-side surface by a roller coater. The adsorbent can be prevented from hydrolyzing with dry air around the coating portion of the coater. Surplus solution can be removed with dry air blown on the surface to make the contamination-resistant property and the appearance better. The chemical adsorbent is bonded to the surface via a siloxane bond to form a thin film. The contamination-resistant float glass is installed in the front door of an apparatus like a toaster oven with the film facing the inside of the oven.

Abstract: This invention provides a contamination-resistant float glass showing even quality in durability and its good quality sufficienty. The film for contamination-resistance is formed only on the top-side surface of a float glass. The surface, free from tin diffused from a float bath, can be identified by ultraviolet irradiation. A solution including a chemical adsorbent like fluoroalkyltrichlorosilane is applied to the top-side surface by a roller coater. The adsorbent can be prevented from hydrolyzing with dry air around the coating portion of the coater. Surplus solution can be removed with dry air blown on the surface to make the contamination-resistant property and the appearance better. The chemical adsorbent is bonded to the surface via a siloxane bond to form a thin film. The contamination-resistant float glass is installed in the front door of an apparatus like a toaster oven with the film facing the inside of the oven.

Abstract: A method for producing an improved quartz glass crucible for pulling up silicon single crystals comprises forming a premolding by feeding powdered silicon dioxide into the mold and by then forming it into a layer along the inner surface of the mold; forming a crucible base body of a translucent quartz layer by heating the premolding from the inner side, thereby partially melting the powdered silicon dioxide, followed by cooling and solidifying the melt; forming a crystallization-promoter containing layer along the internal wall surface of the crucible body by scattering the crystallization promoter on the surface of the internal wall of the crucible body during or after forming the crucible base body; and forming a synthetic quartz glass inner layer by scattering and fusing a powder of silicon dioxide on the crystallization promoter-containing layer that is formed along the internal wall surface of the crucible base body.

Abstract: An excellent quartz glass optical member having stable laser beam resistance, can be obtained by preparing quartz glass in a process having:a first step of subjecting a starting material obtained from silicon halide, alkoxysilane, alkylalkoxysilane, etc. to an oxidizing heat treatment in a temperature range between 600 and 1,500.degree. C., to decrease the hydrogen concentration to 5.times.10.sup.16 molecules/cm.sup.3 or less and at the same time eliminate reducing defects;a second step of subsequently holding the quartz in a hydrogen-containing atmosphere in a temperature range between 200 and 600.degree. C., to establish a hydrogen concentration in the glass of 1.times.10.sup.17 molecules/cm.sup.3 ; anda third step of carrying out a treatment of making the hydrogen concentration of the resultant quartz glass uniform in an atmosphere of air, inert gas, hydrogen, a mixture of hydrogen and inert gas, or a mixture of air and inert gas in a temperature range between 300 and 800.degree. C.

Abstract: This invention relates to a continuous process for producing a web of thin, chemically hardened glass that can be wound on a roll. The process comprises the steps of (i) drawing glass, containing original alkali ions, to form a web of glass having a thickness equal to or lower than 1.2 mm and having a first and second major surface; (ii) directly after or during said drawing, treating both said surfaces of said web with chemical hardening means during less than two hours, replacing said original alkali ions by alkali ions having a larger radius; and (iii) after treating both said surfaces, winding said web on a core.

Abstract: Method of making polarizing glass having integral polarizing and non-polarizing regions disclosed. The method involves applying a protective glass/frit material capable of blocking reducing gas to the surface of the glass to form a desired pattern, exposing the glass to a reducing gas atmosphere to render unprotected glass polarizing, and removing the protective glass/frit material to reveal underlying non-polarizing regions.

Abstract: The present invention provides a process for substantially extending the useful life of fused silica elements used in high energy ultraviolet optical systems. The fused silica bulk material is pre-compacted by illuminating it with radiation prior to final mechanical fabrication and polishing to the required final surface figure. When the optical element is subsequently used in a high energy ultraviolet environment, it will continue to be compacted but at a lower effective rate. As a result, the useful life of fused silica optical elements can be increased substantially.In preferred embodiments the fused silica material is precompacted with multiple passes of short-pulse ultraviolet radiation. Multiple passes can reduce precompaction time. In one example useful life of the fused silica is increased from about 150 days to 3.8 years by about 5 days of precompaction.

Abstract: Method of making polarizing glass having integral polarizing and non-polarizing regions is disclosed. The method involves applying a protective glass/frit material capable of blocking reducing gas to the surface of the glass to form a desired pattern, exposing the glass to a reducing gas atmosphere to render unprotected glass polarizing, and removing the protective glass/frit material to reveal underlying non-polarizing regions.

Abstract: Treatment methods for glass medical adhesive applicators in which a glass applicator is exposed to ammonium sulfate, an acidic gas, a plasma or a silanizing agent in order to remove or coat alkalide materials trapped in the glass.

Abstract: The invention is a medium color gray soda-lime-silica glass composition having excellent ultra violet and infra red absorbing ability. The colorants of the glass composition consist essentially of: greater than 0.5 but less than 0.9 wt. % total iron oxide as Fe.sub.2 O.sub.3 ; 0.1 to 1.0 wt. % manganese compound as MnO.sub.2 ; 0.0005 to 0.003 wt. % selenium as Se; 0.002 to 0.010 wt. % cobalt oxide as Co; up to 1.0 TiO.sup.2 ; the glass composition having, at 4.0 mm. thickness: 485-570 dominant wavelength, less than 5% purity of excitation, 35 to 60% light transmittance using Illuminant A, less than 40% ultra violet transmittance measured over 300-400 nm, and less than 45% infra red transmittance measured over 760-2120 nm.

Abstract: The invention provides a process of obtaining a gradient index type of optical element with profiles of first and second metal component concentrations by the sol-gel method. The process of fabricating a gradient index type of optical element comprises steps of dipping a silicon component-containing wet gel prepared by the sol-gel method in a solution containing an alkoxide of at least one metal component selected from a first group consisting of Ti, Nb, Ta, and Zr or a derivative thereof to thereby impart to the wet gel a concentration gradient with a concentration of the first metal component decreasing from a periphery to a center of the wet gel, allowing at least one metal component selected from a second group consisting of Ba, La, Y, Gd, Sr, Ca, and Zn to be dissolved out of the wet gel to thereby impart to the wet gel a concentration gradient with a concentration of the second metal component increasing from the periphery to the center of the wet gel, and drying, and firing the wet gel.

Abstract: A method of forming an article having a cermet layer on a porcelain substrate, via the steps of (a) providing a substrate made a porcelain comprising one or more crystalline oxide phases dispersed in a glassy matrix, the glassy matrix containing 0.25 to 45.0 weight % of a reducible metal oxide having a reduction potential of between -1.0 and +3.5 E.degree./V; and (b) heating the substrate in a reducing atmosphere to form on at least one surface of the substrate a layer of cermet comprising elemental metal which is a reduction product of the reducible metal oxide. The article may be used as a substrate for magnetic recording disks.

Abstract: A number of unique processes are disclosed for manufacture of sintered high-purity quartz glass products in which a shaped silica body or preform is made from an aqueous slurry of micronized silica particles by gel casting, slip casting or electrophoretic deposition. The silica particles may comprise a major portion by weight of crystalline silica. In one embodiment of the invention the sintered quartz glass is transparent, substantially bubble-free and suitable for scientific or optical uses. In another embodiment the porous silica preform is fired in steam to increase the hydroxyl content and then nitrided in a nitrogen-hydrogen reducing atmosphere. A minute amount of chemically-combined nitrogen in the high-purity quartz glass is sufficient to provide a tremendous improvement in physical properties and an incredible increase in the resistance to devitrification.

Abstract: The present invention provides a method for manufacturing an optical component that have increased transmittance in the ultraviolet region of the spectrum. The method includes the steps of cutting out a part from a block material; polishing optical sides of the part; subjecting the part to heat treatment at a temperature of between 100 and 900.degree. C.; and subjecting the part to acid treatment.

Abstract: A process of manufacturing a silica glass article comprising the steps of: (1) irradiating a silica glass article with electromagnetic waves to generate defects therein; and (2) immersing the thus irradiated silica glass article in an atmosphere comprising a hydrogen gas, thereby providing the resulting silica glass article with a characteristic that is effective for preventing it substantially from increasing its absorption within an ultraviolet region due to ultraviolet ray irradiation. Also disclosed are a silica glass article or a glass fiber produced according to the manufacturing process.

Abstract: The invention relates to a single phase vitreous material and to its production from a melt of a glass-forming multi-component feed mix. The process includes the preparation of a single phase melt in which there are mobile cations from a glass forming feed mix. The melt in passed in contacting relationship with and sequentially between devices made of low electrical resistance material from device to device. These devices are in and complete with the melt and a direct current voltage source an electric circuit. A voltage is regulated in the electrical circuit so that a direct electrical current is created in it and the concentration of the mobile cations in the melt is lowered thereby with reduction on the cathode of the metals of the same kind as the mobile cations. The melt, lowered concentration of the mobile cations, is cooled to produce the material as a structural article. In another embodiment, the anode is separated from the melt by a medium which is substantially inert with respect to the melt.

Abstract: The present provides a method for making glass pressure sensors in batch. First glass plates of appropriate dimensions are scribed. Then electrodes are sputters onto each of the plates, followed by screen printing a frit layer and crossover tabs. The plates are then preglazed and bonded together to form a plurality of sensors. The plates are then scribed and broken along the scribes to form individual sensors.

Abstract: An inner chamber is arranged inside an outer chamber and stores quartz crystal powder. A space is defined between the inner chamber and the outer chamber, and an oxygen gas is introduced into that space. The quartz crystal powder is supplied from the inner chamber into a burner section, together with the oxygen gas. The burner section is also supplied with a flammable gas from a gas control device. The flammable gas contains an NH.sub.3 gas. The heat produced by the combustion of the flammable and oxygen gases fuses the quartz crystal powder supplied from the inner chamber into the burner section. As a result, quartz containing nitrogen is produced. The nitrogen is contained in the fused quartz in an amount which is expressed as 1 to 10% by molar ratio.

Abstract: The invention is directed to a method of producing a chemically pretensioned glass body. In the method, a glass body is provided having a composition in percent by weight on oxide basis: SiO.sub.2 70-85; B.sub.2 O.sub.3 8-15; Na.sub.2 O 1-5; K.sub.2 O 1-<5; Al.sub.2 O.sub.3 1-5; MgO 0-3; SrO+BaO 0-2; CaO 0-3; ZnO 0-3; with CaO+ZnO 2-6; and, ZrO.sub.2 0-3.5. The glass body is placed in an ion exchange salt bath containing at least 90% by weight of potassium salts. The salt bath is maintained at a temperature below the transformation point Tg of the glass defined by the glass composition for a duration of at least 2.0 hr causing potassium ions from the salt bath to migrate into the surface region of the glass body to thereby produce the chemically pretensioned glass body.

Abstract: A porous body containing a silicon component as a starting material of optical element is immersed in a solution containing hydrofluoric acid, taken out from the solution and immersed in a solution containing a metal alkoxide containing a first metal component except silicon or a derivative thereof so that the porous body contains the first metal component in such a concentration gradient that the concentration of the first metal component decreases from a periphery of the porous body toward a center of the porous body. Hydrofluoric acid breaks glass bonds of the porous body, so that the concentration of the first metal component can be securely distributed in a desired gradient. Drying and sintering of the porous body enables producing, for example, a glass having a metal component concentration concavely distributed in its radial direction which is excellent in chromatic aberration suppressing capability.

Abstract: This invention provides a contamination-resistant float glass showing even quality in durability and its good quality sufficienty. The film for contamination-resistance is formed only on the top-side surface of a float glass. The surface, free from tin diffused from a float bath, can be identified by ultraviolet irradation. A solution including a chemical adsorbent like fluoroalkyltrichlorosilane is applied to the top-side surface by a roller coater. The adsorbent can be prevented from hydrolyzing with dry air around the coating portion of the coater. Surplus solution can be removed with dry air blown on the surface to make the contamination-resistant property and the appearance better. The chemical adsorbent is bonded to the surface via a siloxane bond to form a thin film. The contamination-resistant float glass is installed in the front door of an apparatus like a toaster oven with the film facing the inside of the oven.

Abstract: A process for producing a polarizing glass containing shape-anisotropic metallic particles dispersed in an oriented state therein, which comprises drawing a glass preform containing metallic halide particles dispersed therein while its viscosity being held above 2.times.10.sup.6, but below 7.times.10.sup.7 poises; and subjecting the drawn glass to a reducing treatment so that a part or all of the metallic halide particles are reduced to metallic particles, which process enables it to produce a polarizing glass with a high yield from a starting material of a glass containing metallic halide particles, while avoiding glass to breakage or fracture during elongation as well as preventing the elongated metallic halide particles from returning to a spherical shape.

Abstract: Optical waveguide core compositions comprising a core containing two dopants in a silica based glass, wherein one of the dopants is titania. The core composition serves to suppress the presence of Ti.sup.-3 and to preserve refractive index profile shape throughout the preform manufacturing process.

Abstract: The invention provides a process for making a gradient index optical element having a precisely parabolic configuration of refractive index profile. After a concentration profile is imparted across a gel prepared by a sol-gel technique, the concentration profile is fixed. In this case, the treatment with a concentration profile-fixing solution is carried out at a temperature higher than that at which the treatment with a concentration profile-imparting solution is carried out, whereby the rate of fixing the concentration profile is so higher than that of imparting the concentration profile, so that any possible deformation of the concentration profile formed at the concentration profile-imparting step is reduced or inhibited.

Abstract: A lathe for blowing glass. The lathe includes a lower section and an upper section removably attached to the lower section to form a housing. A motor is operably connected to a gear assembly. At least one roller assembly rotatably supports a blowpipe. An air coupling assembly rotatably attached to the gear assembly allows air to pass from a blowhose to an air tube frictionally engaging the blowpipe. A sprinkler system may be provided for cooling the blowpipe while the article is being formed. The speed and direction of rotation of the blowpipe can be manually or remotely controlled by the glassmaker. Thus, the lathe is capable of rotating the blowpipe while air is being provided to the blowpipe to form the article.

Abstract: A porous silica body with a density of 0.1 g/cm.sup.3 to 0.5 g/cm.sup.3 and a density variation of less than 30% is subjected to a first heat-treatment in an ammonia-containing atmosphere, a second heat-sintering in non-oxidizing atmosphere, and further heat-treatment at a temperature in the range of 1400.degree. C. to 2000.degree. C. under an increased pressure of 500 kg/cm.sup.2 or more in a non-oxidizing atmosphere.

Abstract: A gradient index optical element is disclosed which comprises a surface perpendicular to an optical axis, this surface having points of equal refractive index whose connection provides substantially elliptic lines. This gradient index optical element can be produced, for example, by first pouring a raw material sol into a vessel suited for preparing a rodlike base material comprising a surface perpendicular to its lengthwise direction, said surface having the shape of a rectangle, a rhombus or a polygon symmetrical with respect to its center of gravity, each as is, or having a rounded or elliptical corner subsequently converting the sol to a gel, then subjecting the gel to distribution providing treatment and finally drying and firing the distribution providing gel.

Abstract: Mixed colored cullet glass, which generally contains amounts of green, amber and flint (colorless) glasses, is recycled into amber colored glass by regulating the additive amounts of amounts of iron, carbon, sulfur, and sulfur compounds in the mixture to impart the desired reddish-brown hue. The color green may be selectively decolorized from the mixed colored cullet and the mixed colored cullet may be colorized for the color amber, thereby rendering the decolorized mixed colored cullet substantially amber colored for use in amber colored glass production, such as carbon-sulfur soda lime amber glass. The technique of the invention is also used to produce recycled green or flint glass from unsorted mixed colored cullet glass. The invention is particularly useful in producing amber colored containers or bottles for beverages that require protection from the deteriorating effects of light, such as beer.

Abstract: A process for the treatment of a glass to reduce or remove its wettability by gallium is provided, wherein the glass is treated with a silyling agent. Also is provided an apparatus comprising at least one hollow element containing a gallium or gallium based alloy or in which a gallium or gallium based alloy can circulate, wherein the glass forming the hollow element has been treated using the process. The apparatus may be thermometer, barometer or electric switch.

Abstract: Recent UV-lithography is required to provide a fine and sharp pattern with a line width of 0.5 .mu.m or less. The present invention provides a silica glass member adapted for use as an optical element for UV-lithography, by giving consideration to the RMS value of wave front aberration and the slant element of refractive index, which have not been considered in the art. Also there is provided a silica glass member excellent in durability to the ultraviolet irradiation, by introduction of hydrogen molecules at the synthesis of silica glass, instead of the secondary treatment for hydrogen introduction.

Abstract: A method for manufacturing a magnetic recording disk including the steps of forming a film of solution on at least a principal surface of a sheet glass; the solution contains a water soluble inorganic material and a surface active agent; sandwiching both sides of a single sheet glass on which the film is formed or on a laminated structure of plural sheet glasses with a densified sheet with a high flatness to pressure the single glass or laminated structure; and heating and annealing the single sheet glass or laminated structure to flatten it. The end side of the flattened glass substrate is treated with a treating solution containing hydrofluosilicic acid.

Abstract: Pure transparent quartz glass is provided by molding powdery amorphous silica into an article, converting the molded powdery amorphous silica into crystalline silica of high-temperature type cristobalite structure, and then fusing the crystalline silica, the quartz glass containing impurities respectively at a content of not higher than 1 ppm, and an OH group at a content of not higher than 20 ppm, and having a viscosity of 10.sup.12.0 poise or more at 1200.degree. C. The quartz glass is transparent and has high purity, and is excellent in high temperature viscosity characteristics. The quartz glass can be produced at a low cost.