Apparatus for depositing a thin film hermetic coating on a drawn fiber, the apparatus comprising:
- vacuum chamber means;
- a cylindrical magnetron positioned within said vacuum chamber means, the cylindrical magnetron having a longitudinal axis that is substantially coincident with a longitudinal axis of the drawn fiber, the cylindrical magnetron comprising a cylindrical mesh extraction grid coaxially positioned with respect to the drawn fiber to surround the drawn fiber, a cylindrical mesh anode, coextensive with the cylindrical mesh extraction grid, having a diameter greater than the diameter of the cylindrical mesh extraction grid, and coaxially positioned with respect to the drawn fiber to surround the cylindrical mesh extraction grid, a cylindrical cathode, coextensive with the cylindrical mesh extraction grid and cylindrical mesh anode, having a diameter greater than the diameter of the cylindrical mesh anode, and coaxially positioned with respect to the drawn fiber to surround the cylindrical mesh anode, and cylindrical solenoid means, coextensive with the cylindrical mesh extraction grid, cylindrical mesh anode, and cylindrical cathode, having a diameter greater than the diameter of the cylindrical cathode, and coaxially positioned with respect to the drawn fiber to surround the cylindrical cathode, said cylindrical cathode having an inner surface comprising a desired material to be sputtered therefrom and uniformly deposited, through said cylindrical mesh anode and through said cylindrical mesh extraction grid, onto the drawn fiber;
- power supply means for applying selected voltages to the cylindrical cathode, cylindrical mesh anode, cylindrical mesh extraction grid, and cylindrical solenoid means, the application of said selected voltages causing the formation of a cylindrical plasma substantially confined within a volume enclosed within said cylindrical cathode and without said cylindrical mesh anode;
- vacuum control means coupled to the vacuum chamber means for establishing and maintaining a desired vacuum within the vacuum chamber means;
- and
- gas port means coupled to the vacuum control means and vacuum chamber means for admitting and controlling the flow of one or more selected reactive feedstock gases into the vacuum chamber means;
- said cylindrical plasma being operative for dissociating the one or more selected reactive feedstock gases into one or more constituent elements, one or more of which constituent elements reacts with the material sputtered from the inner surface of said cylindrical cathode for uniform deposition as a film onto the drawn fiber;
- said cylindrical solenoid means being operative for trapping plasma electrons within said cylindrical plasma and for increasing the efficiency of ion production;
- and
- said cylindrical mesh extraction grid being operative for accelerating ions or electrons created in said cylindrical plasma toward the drawn fiber for bombardment by said ions or electrons of said film deposited on said drawn fiber, thereby providing control over the stoichiometry of said film.