Fabrication of optical preforms by axial chemical vapor deposition
First Claim
1. A method of producing an optical preform, comprising the steps of forming a flow of a heated gaseous medium through and beyond a heating zone, including inducing a ring-shaped plasma in the heating zone for heating the gaseous medium to a predetermined temperature;
- introducing only into the center of the ring-shaped plasma at least one reactant capable of undergoing a chemical conversion into an optical material soot at the predetermined temperature for the soot to be formed in, and entrained in the flow of the gaseous medium for travel beyond, the heating zone; and
disposing a bait in the flow of the gaseous medium beyond the heating zone for depositing the entrained optical material soot on the bait and thus growing the optical preform.
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Accused Products
Abstract
Hydroxyl free deposition with high efficiency and at a high deposition rate may be achieved, even with use of relatively inexpensive raw materials, by utilizing a ring-shaped plasma activated axial chemical vapor deposition obtaining 100% chemical conversion and fractional volatilization of impurities. The plasma is induced in an annular stream of a plasma-forming gaseous medium, and the reactant or reactants used in the axial chemical vapor deposition are introduced into the center of the ring-shaped plasma to be converted by the heat of the plasma flame into soot which is deposited on a bait. An annular stream of a cooling medium flows outwardly past the plasma flame and is circumferentially centered by an extension of the outer tubular element of a plasma torch in which the plasma is generated. An RF generator which induces the plasma is operated at a frequency exceeding 20 MHz to give the plasma flame the desired ring-sloped configuration.
57 Citations
24 Claims
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1. A method of producing an optical preform, comprising the steps of forming a flow of a heated gaseous medium through and beyond a heating zone, including inducing a ring-shaped plasma in the heating zone for heating the gaseous medium to a predetermined temperature;
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introducing only into the center of the ring-shaped plasma at least one reactant capable of undergoing a chemical conversion into an optical material soot at the predetermined temperature for the soot to be formed in, and entrained in the flow of the gaseous medium for travel beyond, the heating zone; and disposing a bait in the flow of the gaseous medium beyond the heating zone for depositing the entrained optical material soot on the bait and thus growing the optical preform. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatuus for producing an optical preform, comprising
means for forming a flow of a heated gaseous medium through and beyond a heating zone, including means for inducing a ring-shaped plasma in the heating zone for heating the gaseous medium to a predetermined temperature; -
means for introducing only into the center of the ring-shaped plasma at least one reactant capable of undergoing a chemical conversion into an optical material soot at the predetermined temperature for the soot to be formed in, and entrained in the flow of the gaseous medium for travel beyond, the heating zone; and means for positioning a bait in the flow of the gaseous medium beyond the heating zone for depositing the entrained optical material soot on the bait and thus growing the optical preform. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification