Patent ID: 7460752

Claim:
A method of aligning a fixture to a substrate, comprising: a) providing at least one illumination fiber coupled at a first end thereof to a light source, and a plurality of receiver fibers, each receiver fiber coupled, at a respective first end thereof, to a corresponding detector; b) illuminating at least a first portion of a substrate surface with light from a second end of the at least one illumination fiber; c) receiving light reflected from the first portion of the substrate surface at the respective second ends of the receiver fibers, and receiving, at the detectors, a light signal from each of a plurality of receiver fibers; d) determining an amplitude of the light signal from each of the plurality of receiver fibers; e) changing, if the determination of (d) is that the amplitude of the light signal from each of the plurality of receiver fibers is substantially equal and above a predetermined threshold, the x-y-theta position of the at least one illumination fiber and the plurality of receiver fibers, relative to the substrate, by a predetermined amount; f) illuminating at least a portion of a second portion of the substrate surface with light from the second end of the at least one illumination fiber; g) receiving light reflected from the second portion of the substrate surface at the respective second ends of the receiver fibers, and receiving, at the detectors, a light signal from each of a plurality of receiver fibers; h) determining an amplitude of the light signal from each of the plurality of receiver fibers; and i) changing, if the determination of (h) is that the amplitude of the light signal from each of the plurality of receiver fibers is not substantially equal, the x-y-theta position of the at least one illumination fiber and the plurality of receiver fibers, relative to the substrate, back to its position prior to the change of step (e); wherein the substrate includes a field area and at least one target structure.