US 2011/0226019 A1 · Automatic core-alignment for fusion splicing double-clad fibers

Abstract

In aligning ends of optical fibers, e.g. ends of large mode area double-clad fibers (LMA-DCFs), in a fiber optic fusion splicer the best position of the object plane of the optical system for observing images of the cores of the fiber ends are first determined by maximizing the contrast of the core image, in particular the core image peak in intensity profiles. The alignment process may be performed by adjusting the offset distance between the observed cores in some suitable way, e.g. by using a cascade technique. In e.g. a process for prealigning the fiber ends the self-focusing effect of optical fibers can be used to first determine the best object plane position for observing the self-focusing effect and then the very pre-alignment operation can be performed. This may extend the range of image analysis allowing e.g. that alignment, in particular core alignment, can be performed without requiring direct information showing the position of sides or edges of the claddings in captured pictures.

Claims38

Dependent claims

A method of finding an alignment position of an object plane of an optical system, the alignment position suited for capturing pictures along an optical axis of the optical system, when aligning two optical fiber ends with each other, the optical system having an object plane, the method comprising the steps of:

setting the object plane in an initial position,
capturing, using the optical system, a picture comprising an image of one of the two optical fiber ends,
evaluating said image in the captured picture,
displacing, based on the evaluating, the object plane from the initial position along the optical axis to find an alignment position for said one of the two optical fiber ends in which alignment position of the object plane, in a picture captured by the optical system for the alignment position and in the image of said one of the two optical fiber ends, a local contrast value for the image area of the core of said one of the two optical fiber ends, in particular the difference between the brightness, the local contrast value in particular being the maximum brightness, of the image area of the core of said one of the two optical fiber ends and the brightness, in particular the maximum brightness, of longitudinal, relatively bright, separate image areas adjacent to the image of the core of said one of the two optical fiber ends in said image, has a maximum value or deviates from a maximum value by at most a predetermined value.

1 more element

A method of aligning two optical fiber ends with each other using an optical system for capturing pictures along an optical axis of the optical system, the optical system having an object plane, the method comprising the steps of:

finding an alignment position of the object plane for at least one of the two optical fiber ends,
capturing, using the optical system, with the object plane of the optical system set in the alignment position for said at least one of the fiber ends, a picture, or pictures respectively, of the two optical fiber ends,
evaluating the captured picture/pictures to find a lateral offset between the cores of the two fiber ends as seen along the optical axis of the optical system, and
displacing the two fiber ends in relation to each other in a plane perpendicular to the optical axis to make said lateral offset equal to a desired value, in particular equal to zero.

1 more element

Dependencies are inferred from the claim text.

Automatic core-alignment for fusion splicing double-clad fibers

Life of this patent

Automatic core-alignment for fusion splicing double-clad fibers

Life of this patent

Abstract

Claims38