Full-field heterodyne polariscope with an image signal processing method for principal axis and phase retardation measurements.

We develop a heterodyne polariscope for measuring the two-dimensional principal axis and phase retardation in a linear birefringence material using novel three-frame and two-frame integrating-bucket methods and a CCD. By using a complex programmable logic device to provide an external trigger to the CCD, integrating buckets with multiple frames are achieved. The advantages of the proposed three-frame and two-frame integrating-bucket methods include a simpler signal processing algorithm based on fewer frames and the elimination of flyback error caused by a sawtooth modulation signal at higher frequencies.