Algorithm study of the measurement of the radius of curvature of fiber optic connector end faces

With the rapid development of fiber communications, the fiber optic connector has become an indispensable no-source device, among which PC-type connector is most commonly used. As radius of curvature (ROC) of the connector end face is one of the three main geometric parameters affecting insertion and return losses, how to measure accurately the ROC has become an important issue in the field. In this paper, an algorithm, overlapping averaging 4-bucket method (OAF), is introduced to measure the parameter. Correspondingly, calculation of the phase principal values of the object wave-front and reconstruction of the spherical profile of the connector end face are analyzed, with simulation results given. Also analyzed is the influence of the shifting error of the phase shifter on the ROC measurement, with a curved surface figure for their relationship obtained. Meanwhile, a comparison is made between the errors developed by the 4-bucket algorithm (FBA) and OAF. It is indicated by the results that, OAF is superior to FBA in the suppression of the shifting error, and that, over a general range of calibration error and nonlinear displacement error both equal to or less than 8%, the ROC measurement error with OAF is less than 2.3×10-4.