Spectropolarimetric measurement based on a fast-axis-adjustable photoelastic modulator

Area of Science:

• Optics and Photonics
• Polarimetry
• Imaging Technology

Background:

• Spectropolarimetric imaging is crucial for analyzing light polarization properties.
• Traditional methods often involve mechanical components or complex setups.
• A need exists for efficient and adaptable polarimetric measurement techniques.

Purpose of the Study:

• To develop and investigate a fast-axis-adjustable photoelastic modulator (Faa-PEM).
• To present a spectropolarimetric imaging method utilizing the Faa-PEM and an acousto-optic tunable filter.
• To demonstrate a system capable of measuring Stokes parameters (I, Q, U) without mechanical rotation.

Main Methods:

• Development of a Faa-PEM with adjustable retardation amplitude and fast-axis direction via electronic control.
• Integration of the Faa-PEM with an acousto-optic tunable filter for spectropolarimetric imaging.
• Utilizing the Faa-PEM's adjustable parameters to derive Stokes parameters (I, Q, U) of incident light.
• Employing a general area array detector, eliminating the need for high-frequency components.

Main Results:

• Theoretical simulations indicate relative errors (ΔI/I, ΔQ/Q, ΔU/U, ΔDoLP/DoLP) below 5.6% and angular deviation error (ΔAoLP) below 0.2° under specific conditions.
• Prototype testing confirmed high accuracy, with average absolute relative errors for the degree of linear polarization (DoLP) at 0.36%.
• Average absolute deviation error for the angle of linear polarization (AoLP) was measured at 0.048°.

Conclusions:

• The developed Faa-PEM and spectropolarimetric imaging method offer a robust and accurate approach to polarization measurement.
• The system's ability to adjust parameters electronically and use standard detectors simplifies implementation.
• This technology holds significant potential for advancements in spectropolarimetric imaging applications.