Stray light analysis and suppression design for spectral modulation polarization detection system

Spectral modulation polarization detection technology employs a frequency carrier method to achieve high-precision modulation and demodulation of linear polarization information in the spectral dimension. The design of the multi-plate modulation module makes stray light a significant factor affecting polarization detection accuracy, stray light analysis and suppression must be performed. A ray-tracing model of the spectral modulation polarization detection module was established, and stray light simulation analysis was conducted to identify the primary stray light paths, followed by the design and analysis of stray light suppression structures. Quantitative simulation analysis of stray light within and outside the field of view was performed using the stray light coefficient and point source transmittance. The results show that stray light within the field of view was reduced to below 0.5%, and stray light outside the field of view with an angle greater than 5° was reduced by five orders of magnitude.