Simultaneous measurement of roll and pitch angular displacements based on polarization interferometry

The paper presents an innovative approach for measuring roll and pitch angular displacements simultaneously by using dual-beam polarization interferometer. Dual beams incident on the birefringent crystal induce phase differences variation due to the birefringent crystal's roll and pitch angular displacements. Developing a polarization interferometer and phase analysis techniques, this system can measure the phase differences variation to determine the roll and pitch angular displacements. This approach extends the limited measurement range of existing interferometers to several degrees. Following uncertainty evaluation, the proposed system achieved a roll angle and pitch angle resolution of 2.5 arcsec and 21.6 arcsec, respectively. This paper also discusses the issue of nonlinear periodic error and the system's sensitivity.