Patent ID: 8317412

Claim:
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: illuminating a first side of one of the two optical fibers ends with a collimated light source; setting the object plane in an initial position, wherein the initial position is selected to be at or at a relatively small distance of a second side of the one of the two optical fiber ends that faces the optical system and that then the object plane is displaced away from said one of the two optical fiber ends by one or more predetermined steps, in each predetermined step a picture being captured and evaluated to find a brightness of a truncated centrally located relatively bright area, a first position taken when the found brightness is larger than a predetermined threshold or in the middle of or inside a range of the predetermined steps in which the found brightness is larger than the predetermined threshold, wherein said predetermined threshold corresponds to the saturation level of an imaging sensor used to capture the pictures, evaluating said image in the captured picture taken at the first position, and displacing, based on the evaluating, the object plane from the first position along the optical axis to find the alignment position of the object plane where the alignment position of the object plane is found when the truncated centrally located relatively bright area has a width with a minimum value or deviates from a minimum value by at most a predetermined value, wherein the alignment position corresponds to a self-focus plane of said one of the two optical fiber ends.