Corning Incorporated

Alain Kerdoncuff

Michel Prassas

Alexandre Michel Mayolet

Allan Mark Fredholm

Claude Fm Gille

Claude F M Gille

The present invention relates to the manufacturing of high purity optical flouride crystals, the making of purified optical flouride crystal feedstocks and to the anionic purification of optical fluoride crystalline materials. The invention relates generally to methods for removing oxide impurities from optical fluoride crystal feedstocks. More specifically, the invention relates to a method for preparing purified optical fluoride crystal feedstocks and the use of the feedstock in manufacturing VUV<200 nm transmission optical fluoride crystals for VUV lithography/laser systems.

Method of making high purity optical fluoride crystals

The optical fluoride crystal treatment device of the invention includes a enclosure ( ) separating the device from its external environment, heating means to heat and keep the internal volume ( ) of said enclosure ( ) at a predetermined temperature, at least one hollow platform ( ) delimiting an internal chamber ( ) whose upper wall ( ) bears at least two independent diffusers ( ) each delimiting a cavity ( ) able to receive a unitary quantity ( ) of said optical fluoride crystal substance, each of said cavities ( ) communicating with said internal chamber ( ) of the corresponding platform ( ), a gas supply source containing said reactive gas, and means ( ) for distributing said gas containing said reactive gas from said supply source to the inside of the internal chamber of each platform and having means ( ) for regulating the pressure of said distributed gas. This optical fluoride crystal treatment device is preferably used to carry out anionic purification with a reactive gas formed of a fluoridation gas, a fluoride powder of an alkaline metal or alkaline-earth metal in the making of optical fluoride crystals.

Method of making a <250 nm wavelength optical fluoride crystal and device

According to the invention, a) at least the first and second compositions of this material in the fluid phase are prepared, b) a sheet (,) of the first composition is poured continuously onto a flat support (,), c) a sheet (,) of the second composition is poured continuously onto sheet (,) of the first composition, and d) the thermal interdiffusion of the materials of the two sheets is ensured so as to obtain the desired gradient of composition in the cooled bar.

Method of making an article having a gradient composition

A double crucible fiber fabrication system employing a rod to control flow of the core material to produce a core of desired diameter. The rod fits closely within the inner crucible and moves at a speed necessary to produce a core material flow rate which will produce a desired core diameter. Control of the rod speed produces good control of core diameter for a wide variety of different core materials. It is also possible to control the rod speed in order to compensate for capillary effects and leakage of core material. Furthermore, control of the rod speed allows fabrication of a fiber having a core diameter which varies as desired throughout a single fiber.

Method of controlling an extrusion of glass to make an optical fiber

Method for making an article having a gradient of composition

The material is in a fluid state at a predetermined temperature above the ambient temperature. According to the invention: a) at least two different compositions of this material in the fluid state are prepared; b) simultaneously and concentrically both the core of the rod with the aid of one of the compositions and a sheath enveloping this core with the aid of another composition are cast; and c) the casting is then taken to a temperature at which it solidifies to constitute the rod. Advantageously, the section of the casting is made to grow by its passing through a cylindrical mold shaped to define the final section of the rod. Application to the manufacture of a glass rod presenting a cross-sectional refractive index gradient.

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Vincennes, France

Alain Kerdoncuff