This paper discusses the challenges and methods for measuring high extinction ratio polarizers (exceeding 10^6), particularly in systems where precise measurement is crucial. The extinction ratio of a polarizer is significantly influenced by test system geometry, which complicates accurate assessments for high-performance polarizers. The authors present techniques for measuring high purity polarizers without relying on a perfect reference polarizer with infinite extinction ratio. Additionally, they describe methods for computing and rank-ordering the performance of multiple polarizers. Measurement results are provided for several types of polarizers, including Glan-Thompson polarizers, dichroic glass polarizers, and Meadowlark Optics Ultra Broadband Polarizers, demonstrating the accuracy and applicability of the methods discussed. These advancements are essential for precision optical systems and polarization control applications in scientific and industrial fields.

Keywords: extinction ratio, high purity polarizers, polarization measurement, Glan-Thompson polarizers, dichroic glass polarizers, Ultra Broadband Polarizers, Meadowlark Optics, test system geometry, polarization control, optical systems.