Signal and noise analysis for chiral structured illumination microscopy

Area of Science:

• Optics and Photonics
• Biophysics
• Materials Science

Background:

• Chiral structured illumination microscopy (CSIM) enables sub-wavelength imaging of fluorescent chiral domains.
• CSIM combines structured illumination microscopy, fluorescence-detected circular dichroism, and optical chirality engineering.
• Weak circular dichroism in natural chiral molecules leads to low differential fluorescence, often obscured by noise, limiting image fidelity.

Purpose of the Study:

• To systematically analyze the impact of noise on the quality and resolution of CSIM-acquired chiral domain images.
• To provide an analytical framework for understanding signal-to-noise ratio (SNR) in reconstructed CSIM images.
• To assess the practical feasibility of CSIM under various experimental conditions and suggest SNR enhancement strategies.

Main Methods:

• Analytical description of the SNR in the Fourier domain for CSIM.
• Numerical simulations to verify theoretical SNR calculations.
• Evaluation of CSIM performance in different experimental scenarios.

Main Results:

• Noise significantly degrades the quality and resolution of chiral domain images reconstructed by CSIM.
• Theoretical calculations accurately predict the SNR in the Fourier domain.
• Identified key factors influencing CSIM feasibility and image fidelity.

Conclusions:

• Noise is a critical factor affecting CSIM performance, particularly for samples with weak circular dichroism.
• The developed analytical framework aids in understanding and predicting CSIM image quality.
• Proposed strategies can enhance SNR, improving the applicability of CSIM for imaging delicate chiral structures.