Vision based ultra-precision centering of optical fibers for microlens fabrication

An optical fiber is mounted on a precision spindle, that can be indexed as well as speed controlled, in readiness for precision microlens grinding. A cluster of piezoelectric actuators, mounted on the spindle itself, carry out the crucial task of centering the fiber. Together with the indexing carried out using the spindle drive motor, the piezoelectric actuators allow position and angle adjustments in two perpendicular plains to achieve complete centering. An imaging system, using sub-pixel localization methods and a high magnification lens, simultaneously senses the eccentricity and angular misalignment of the optical fiber. A closed loop multi-axis centering controller has been implemented to achieve eccentricities and angular misalignments within 500 nm and 0.02°, respectively.