The CCD micro-imaging system is employed to get the polarization axis from the cross-section image of Panda PM fiber.The edge points of stress rods are detected by the sub-pixel edge detector based on Hessian matrix.By linking the two centers of the ellipses that are fitted with the sub-pixel edge points,the polarization axis is got.Consequently,not only the automatic detection of the polarization axis but also the accurate calculation of the angle between the PM fiber polarization axis and the orientation ...