Full-field and full-range sequential measurement of the slow axis angle and phase retardation of linear birefringent materials.

A method is proposed for obtaining full-range sequential measurements of the slow axis angle and phase retardation of linear birefringent materials (LBMs) using a full-field heterodyne interferometer with a charge-coupled device (CCD) camera and an image processing algorithm based on a three-frame integrating-bucket method. The dynamic ranges of the principal axis and phase retardation measurements extend from 0 degrees to 180 degrees and from 0 degrees to 360 degrees, respectively. The proposed method not only enables full-range measurements of the slow axis angle to be obtained, but also allows a decision to be made as to whether the principal axis labeled by the manufacturer is the slow axis or the fast axis. The standard deviations of the slow axis angle and phase retardation measurements are found to be 0.14 degrees and 0.27 degrees, respectively. In addition, it is shown that the noises induced by environmental disturbances are reduced by elimination of the dc component of the output light intensity in the image processing algorithm. We also investigate the sensitivity of the measured error caused by the orientation of LBM. (C) 2009 Optical Society of America