Dynamic calibration of a channeled spectropolarimeter for extended temperature stability

Benjamin D. Chrysler, Yukitoshi Otani, Nathan A. Hagen, Frans Snik, Julia M. Craven, Joseph A. Shaw
2019 Polarization Science and Remote Sensing IX  
Dynamic calibration of a channeled spectropolarimeter for extended temperature stability," Proc. ABSTRACT Channeled Spectropolarimeters (CHSP) are compact optical instruments that have potential for making precise polarization measurements without any moving parts. While most spectropolarimeters use rotating elements to make measurements, CHSPs use mechanically fixed thick retarders to modulate the Stokes vector onto the spectrum of light. In realistic applications, CHSPs must have calibration
more » ... lgorithms that give stable measurements in a variety of environmental conditions. Previous researchers developed a self-calibration algorithm that uses redundant channel information to compensate temperature-induced phase fluctuations in real-time without any additional reference measurements. In this paper we discuss the stability of the selfcalibration technique. We identify a mathematical ambiguity in the algorithm that limits the range of temperatures over which the algorithm is stable. For a 60 :120 channeled spectropolarimeter with quartz retarders, the stable temperature range is only 27 o C and is not suitable for many applications outside of the laboratory. We propose and demonstrate a modified algorithm that uses the slope of the phase to remove the mathematical ambiguity and extend the temperature range of the system. The demonstration shows stable operation over a 41 o C temperature range and shows promise for increasing stability over a temperature range suitable for extreme terrestrial conditions.
doi:10.1117/12.2528078 fatcat:p36xb6a72nd5dd7avq3rd47pye