Jerald Benjamin Dotson

US Patent:

52836282, Feb 1, 1994

Filed:

Dec 31, 1991

Appl. No.:

7/816491

Inventors:

Jerald B. Dotson - Los Angeles CA
Jerry D. Nease - Wilmington NC
Bruce W. Reding - Elmira NY

Assignee:

Corning Incorporated - Corning NY

International Classification:

G01B 902

US Classification:

356355

Abstract:

A method for measuring the diameter of a transparent filament is provided which is substantially insensitive to ellipticity of the filament. The method comprises using an interference technique to measure the filament diameter at two locations which are spaced apart by an amount such that a plot of diameter versus angle of rotation for an elliptical filament calculated at the first location is approximately 90. degree. out of phase from the same plot calculated at the second location. Due to the phase difference, the average of the two measurements is substantially insensitive to ellipticity. For measurement apparatus comprising one laser and two detectors and for optical waveguide fibers having a cladding composed of fused silica, the two locations can be about 123. degree. apart. In other embodiments, a method for characterizing the non-circularity of a filament is provided. Apparatus for practicing the foregoing methods is also disclosed.

US Patent:

51856360, Feb 9, 1993

Filed:

Dec 31, 1991

Appl. No.:

7/816883

Inventors:

Leslie J. Button - Big Flats NY
Jerald B. Dotson - Los Angeles CA
Bruce W. Reding - Elmira NY
Christopher W. Wightman - Corning NY

Assignee:

Corning Incorporated - Corning NY

International Classification:

G01N 2188
G01N 2189

US Classification:

356 731

Abstract:

Methods for deteting defects, such as, holes or voids, in optical waveguide fibers are provided. The methods employ far-field interference patterns produced by transversely illuminating the fiber with a laser beam. Holes in the fiber produce a characteristic peak in the spatial frequency spectrum of the interference pattern which subdivides into two peaks which migrate in opposite directions as a hole grows in size. Holes also produce a characteristic increase in the total power of the interference pattern, the amount of the increase being a linear function of the size of the hole for holes having a diameter less than about 60% of the diameter of the fiber. The hole detection methods are incorporated in an overall system for controlling the drawing of optical waveguide fibers.