Characterization for imperfect polarizers under imperfect conditions.

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Polarizers are crucial optical components.
• Accurate measurement of polarizer performance, including extinction ratio and transmittance, is essential for various applications.
• Existing methods may be susceptible to errors from incident light polarization and component misalignment.

Purpose of the Study:

• To formulate principles for measuring polarizer extinction ratio and transmittance using Mueller matrix methods.
• To develop and validate techniques for correcting measurement errors.
• To establish algorithms for deducing depolarization of multiple polarizers.

Main Methods:

• Utilized the principal Mueller matrix, incorporating polarization and depolarization.
• Devised zone average and null methods to correct for errors caused by partially polarized incident light and polarizer misalignment.
• Established algorithms for mutual calibration and depolarization deduction of three polarizers.

Main Results:

• The extinction ratio was found to be approximately half of the depolarization.
• Contrast was determined to be the inverse of the extinction ratio.
• The null method, especially with a laser source, proved effective for measuring high-contrast polarizers.
• The developed methods were successfully tested on wire-grid polarizers in the 3-5-microm wavelength region.
• Contrasts obtained using both laser and lamp sources agreed.

Conclusions:

• The Mueller matrix approach provides a robust framework for polarizer characterization.
• The zone average and null methods effectively mitigate common measurement errors.
• Accurate depolarization and contrast measurements are achievable, even for high-performance polarizers.