Corning Glass Works

Che-Kuang Wu

Roger F Bartholomew

Leon M Sanford

Thomas H Elmer

Joseph F Mach

A method for providing a dispersion of a photosensitive silver and chlorine-containing polyphosphate in the pores of a porous 96% silica glass, and a photosensitive product thus produced, are described. The method includes introducing NaCl and KH.sub.2 PO.sub.4 into the pores using at least one liquid vehicle and at least partly removing the liquid vehicle from the pores. Thereafter, AgNO.sub.3 is introduced into the NaCl and KH.sub.2 PO.sub.4 -containing pores using an liquid vehicle before heating the porous glass support to remove remaining liquid vehicle and to react the NaCl, KH.sub.2 PO.sub.4, and AgNO.sub.3 to form a photosensitive silver and chlorine-containing polyphosphate material in situ in the pores of said support.

Method of making photosensitive porous glass

A photosensitive material in the form of a silver and chlorine-containing polyphosphate which exhibits permanent visible darkening on exposure to ultraviolet or short wavelength visible light, is described.

Photosensitive polyphosphate comprising Ag and Cl

This invention is concerned with hydrated glass articles having base compositions within the Na.sub.2 O and/or K.sub.2 O-ZnO-Al.sub.2 O.sub.3 -SiO.sub.2 -Cl field and having at least a surface layer thereon containing Ag-AgCl crystals which impart photo-anisotropic effects to the glass articles. Silver ions are introduced into the surface layer through a solution ion exchange process with sodium and/or potassium ions of the parent glass. The silver remains in the ionic state until exposure to ultraviolet radiation which results in the development of silver-containing aggregates, i.e., Ag-AgCl, via a photolytic reaction. The aggregates contribute to photo-anisotropic absorption bands which are centered around 340 nm and 700 nm. Polarization of the photo-dichroic and photo-birefringent effects of the inventive products can be altered reversibly between two arbitrary directions without fatigue. The photo-anisotropic image can be read cyclically essentially indefinitely without destruction. The product of the invention is eminently suitable as a photosensitive medium for storing optical information.

Photosensitive colored glasses exhibiting alterable photo-anisotropic

The instant invention is directed to a method for writing and erasing images in the surface of a photosensitive glass which demonstrates photoanisotropic behavior at a mega Hz or higher rate. This is accomplished by utilizing an erasing beam of linearly-polarized red light having about a 45.degree. change in the direction of polarization from that of the writing beam. Also, this invention provides a method for preventing the alteration of an image written into said glass surface, the method involving exposing the area of the image to ultraviolet radiation.

Method for optical recording in photo-dichroic glass surfaces

This invention is concerned with hydrated glass articles having base compositions within the Na.sub.2 O and/or K.sub.2 O--ZnO--Al.sub.2 O.sub.3 --SiO.sub.2 --Cl field and having at least a surface layer thereon containing Ag--AgCl crystals which impart photoanisotropic effects to the glass articles. Silver ions are introduced into the surface layer through a solution ion exchange process with sodium and/or potassium ions of the parent glass. The silver remains in the ionic state until exposure to ultraviolet radiation which results in the development of silver-containing aggregates, i.e., Ag-AgCl, via a photolytic reaction. The aggregates contribute to photo-anisotropic absorption bands which are centered around 340 nm and 700 nm. Polarization of the photo-dichroic and photo-birefringent effects of the inventive products can be altered reversibly between two arbitrary directions without fatigue. The photo-anisotropic image can be read cyclically essentially indefinitely without destruction. The product of the invention is eminently suitable as a photosensitive medium for storing optical information.

Method of making photosensitive colored glasses exhibiting alterable

This invention is concerned with the preparation of glass articles containing silver ions which exhibit thermoplastic properties and may, optionally, demonstrate photosensitivity to ultraviolet radiation. Such articles are produced through the exchange of Ag.sup.+ ions for Na.sup.+ and/or K.sup.+ ions in a hydrated Na.sub.2 O and/or K.sub.2 O--SiO.sub.2 glass. The articles will demonstrate photosensitivity when the compositions thereof also contain halide ions.

Method for making silver-containing glasses exhibiting thermoplastic

The present invention is directed to the preparation of hydrated glasses in the Na.sub.2 O-K.sub.2 O-PbO-SiO.sub.2 base composition system containing an amount of BaO and/or Y.sub.2 O.sub.3 and/or ZnO and/or ZrO.sub.2 effective to cause the hydrated glass to be essentially colorless. Such glasses are transparent, exhibit refractive indices higher than 1.60, and which demonstrate intrinsic thermoplastic properties thereby enabling such to be readily molded into optical quality components at relatively low temperatures. The operable glasses in the anhydrous state consist essentially, in mole percent on the oxide basis, of 8-18% Na.sub.2 O, 2-6% K.sub.2 O, 10-23% Na.sub.2 O + K.sub.2 O, &gt;15 but &lt;21% PbO, 55-67% SiO.sub.2, the mole ratio PbO:SiO.sub.2 being between 0.225-0.3, and an effective amount of BaO and/or Y.sub.2 O.sub.3 and/or ZnO and/or ZrO.sub.2 up to the indicated maxima of 5% BaO, 5% Y.sub.2 O.sub.3, 8% ZnO, and 5% ZrO.sub.2, BaO + Y.sub.2 O.sub.3 + ZnO + ZrO.sub.2 not exceeding 10%.

High refractive index hydrated glasses

A glass article having an optical quality surface smoothness can be formed by molding a 'silanol' glass material against a die having a molding surface which is a mirror of that required for the glass article, thereby obviating glass grinding and polishing steps. The article is prepared by first forming an anhydrous base glass comprising, in mole percent on the oxide basis, about 72 to 82% SiO.sub.2, 10 to 17% Na.sub.2 O and/or K.sub.2 O, and 5 to 15% of an oxide or oxides selected from ZnO and PbO. The base glass may include up to 5% Al.sub.2 O.sub.3 and up to 3% of B.sub.2 O.sub.3, BaO and/or MgO. The anhydrous base glass is then hydrated to include a water content ranging from 0.5 to 10% by weight to form a 'silanol' glass. That glass is then molded against the die surface at a temperature ranging from about 250.degree. C. to 500.degree. C. and a pressure ranging from about 4,000 to 20,000 psi for a period of time sufficient to replicate the surface smoothness of the die on the glass and, depending on the molding process, yield a glass article containing about 0.5 to 10% by weight of 'tightly' bound total water.

Method for preparing optical articles from hydrated glasses

An optical glass article having a desired surface figure and demonstrating maximum theoretical light transmission can be prepared by forming a base anhydrous glass of defined compositional ranges, hydrating the glass, partially dehydrating the glass at a temperature above the softening point and, using an inert gas, at a pressure above the vapor pressure of water contained therein, and then molding a preformed blank of the glass against a die having a desired optical quality surface figure, the molding being under conditions sufficient to transfer the surface figure of the die to the glass. The base glass comprises, in mole percent, about 70 to 82% SiO.sub.2, 10 to 17% Na.sub.2 O and/or K.sub.2 O, and 5 to 15% of an oxide or oxides selected from ZnO and PbO. The water content of the partially dehydrated glass ranges from about 3 to 8 wt. percent and the molded glass has a substantially uniform refractive index throughout its bulk. Homogeneous distribution of the water throughout the glass bulk appears to be assured by limiting the total water content to a range at which the diffusion coefficient of the water species (H.sub.2 O, H.sup.+, and OH.sup.-) exhibits the greatest dependence on the total water concentration (i.e. the range at which the coefficient is a quasi-step function).

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Horseheads, NY, United States of America

Che-Kuang Wu