Ferrule-core concentricity measurement systems and methods

Patent metadata

Field	Value
Publication number	US-2015177097-A1
Application number	US-201414571557-A
Country	US
Kind code	A1
Filing date	Dec 16, 2014
Priority date	Dec 19, 2013
Publication date	Jun 25, 2015
Grant date	—

Abstract

Systems and methods of measuring ferrule-core concentricity for an optical fiber held by a ferrule are disclosed. The method includes: generating ferrule distance data by measuring distances to a ferrule outside surface as a function of rotation angle using a distance sensor and rotating either the ferrule or the distance sensor about an axis of rotation that is off-center from the true ferrule axis; aligning the axis of rotation with the fiber core; using the ferrule distance data to determine a position of the true ferrule center relative to the optical fiber core; and measuring the concentricity as the distance between the true center of the ferrule and the optical fiber core.

First claim

What is claimed is:

1 . A system for measuring a concentricity between an optical fiber core of an optical fiber held in a central bore of a ferrule and a true center of the ferrule, wherein the ferrule has a ferrule outer surface and a ferrule front end, and wherein a section of the optical fiber resides in the central bore of the ferrule at the ferrule front end, the system comprising:
a movable ferrule holder configured to hold the ferrule; a light source configured to be optically coupled to the optical fiber and emit light that travels through the optical fiber core and out of a front end of the optical fiber; a distance sensor arranged to measure a ferrule distance to the ferrule outer surface; a core sensor arranged to receive and detect light emitted from the core of the optical fiber at the ferrule front end; a rotatable support member that supports the distance sensor and the core sensor relative to the ferrule, the rotatable support member being configured to simultaneously rotate the distance sensor and core sensor about an axis of rotation that is generally aligned with the optical fiber core at the ferrule front end, wherein the distance sensor is configured to measure ferrule distance data during rotation and the core sensor is configured to measure core location data during rotation; and a computer that receives the ferrule distance data and the core location data and that calculates therefrom the true center of the ferrule and the concentricity as a distance between the optical fiber core and the true center of the ferrule.

2 . The system according to claim 1 , wherein the core sensor includes:
a light-collection optical system that collects the light emitted by the core; a sensing optical fiber having a front end that receives the collected light; and a photodetector optically coupled to the sensing optical fiber and that detects the collected light from a back end of the sensing optical fiber.

3 . The system according to claim 2 , wherein the light-collection optical system is configured to be substantially doubly telecentric.

4 . The system according to claim 1 , wherein the core location data comprises optical power data, and wherein the optical fiber core and the axis of rotation are aligned such that the optical power data is substantially constant.

5 . The system according to claim 1 , wherein the rotatable support member rotates between rotation angles in the range 0°≦θ≦360°.

6 . The system according to claim 1 , wherein the core sensor includes:
a light-collection optical system that collects the light emitted by the optical fiber core and forms an image of the front end of the ferrule and the optical fiber core; and a two-dimensional (2D) image sensor that receives the image and forms therefrom a corresponding digital image.

7 . The system according to claim 1 , wherein the core sensor includes:
a light-collection optical system that collects the light emitted by the optical fiber core; a sensing optical fiber having a front end that receives the collected light and an opposite back end; a reflecting member arranged at the back end of the sensing optical fiber and that reflects the collected light back through the optical fiber and the light-collection optical system and to the optical fiber core; a light-redirecting element optically coupled to the optical fiber and that redirects the light from the light-collection optical system; and a photodetector optically coupled to the light-redirecting member and that detects the light from the light-redirecting element.

8 . The system of claim 1 , wherein the distance sensor is selected from the group of distance sensors comprising: a laser triangulation gauge, a spectral interference gauge, a capacitance distance gauge, and an interferometer gauge.

9 . The system of claim 1 , wherein the core location data comprises either optical digital images of the core and ferrule front end or power measurements of light transmitted by the optical fiber core.

10 . A method of measuring a concentricity between an optical fiber core of an optical fiber held by a ferrule and a true center of the ferrule, comprising:
generating ferrule distance data by measuring distances to a ferrule outside surface as a function of rotation angle using a distance sensor and rotating either the ferrule or the distance sensor about an axis of rotation that is off-center from the true ferrule axis; generating core location data about the optical fiber core by coupling light from the optical fiber core into a core sensor; using the ferrule distance data and core location data to determine a position of the true ferrule center relative to the optical fiber core; and measuring the concentricity as the distance between the true center of the ferrule and the optical fiber core.

11 . The method according to claim 10 , wherein using the ferrule distance data and core location data to determine the position of the true ferrule center relative to the optical fiber core further comprises:
aligning the axis of rotation with the optical fiber core based on the core location data.

12 . The method according to claim 11 , wherein aligning the axis of rotation with the fiber core includes:
measuring an amount of optical power emitted by the optical fiber core and received by the core sensor, wherein the core sensor aligned with the axis of rotation during said rotating, and wherein the measured amount of optical power varies as a function of the rotation angle; and adjusting a relative position the optical fiber core and the core sensor during said rotating until the amount of optical power measured by the core sensor during said rotating is substantially constant as a function of the rotation angle.

13 . The method according to claim 12 , wherein measuring an amount of optical power emitted by the optical fiber core further comprises:
passing light from the optical fiber core to a second optical fiber to travel therein; reflecting the light traveling in the second optical fiber back through the second optical fiber in the opposite direction to the optical fiber core to travel therein; and extracting and detecting the reflected light traveling in the optical fiber core.

14 . The method according to claim 10 , wherein generating core location data comprises measuring a path of the optical fiber core during the rotating of either the ferrule or the distance sensor about the axis of rotation.

15 . The method according to claim 14 , wherein measuring the path of the optical fiber core includes capturing digital images of the ferrule front end.

16 . The method according to claim 14 , wherein measuring the path of the optical fiber core includes measuring amounts of optical power optically coupled from the optical fiber core into the core sensor.

17 . The method according to claim 10 , wherein using the ferrule distance data and core location data to determine the position of the true ferrule center relative to the optical fiber core comprises:
(a) using the ferrule distance data to determine the true ferrule center; and (b) aligning the true ferrule center with the axis of rotation; and (c) determining a distance of the optical fiber core from the true ferrule center based on core location data measured after step (b).

18 . The method according to claim 10 , further comprising supporting the distance sensor and the core sensor relative to the ferrule with a rotatable support member, and rotating the support member about the rotation axis.

19 . Th

Assignees

• Corning Optical Comm Llc

Inventors

• Clarke Sterling Michael
• Costello Iii John Joseph
• Hong En
• Piech Garrett Andrew
• Webb Michael Brian
• Zambrano Elvis Alberto

Classifications

• G01B11/14

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G02B6/3834 Primary

  Means for centering or aligning the light guide within the ferrule · CPC title

• G02B6/3843

  with auxiliary facilities for movably aligning or adjusting the fibre within its ferrule, e.g. measuring position or eccentricity (testing the alignment of axes, including eccentricity, G01B11/27) · CPC title

• G02B6/385 Primary

  Accessories for testing or observation of connectors (means for centering or aligning the light guide within the ferrule with auxiliary facilities for movably aligning or adjusting the fibre within its ferrule, measuring position, eccentricity G02B6/3843; mechanical features associated with the optical testing of optical fibres G01M11/088) · CPC title

• G01M11/33 Primary

  with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face · CPC title