Method for artifact-free circular dichroism measurements based on polarization grating

Area of Science:

• Spectroscopy
• Optical Physics
• Materials Science

Background:

• Conventional circular dichroism (CD) spectroscopy often suffers from artifacts.
• Anisotropic samples and nonideal optical components introduce significant errors.
• Accurate real-time CD measurements are crucial for various scientific disciplines.

Purpose of the Study:

• To develop a simple and effective method for real-time circular dichroism (CD) measurements.
• To overcome limitations of conventional spectrometers, particularly concerning sample anisotropy and optical element imperfections.
• To enable parallel spectral evaluation of true CD spectra.

Main Methods:

• A single polarization holographic grating was employed.
• The grating's first diffraction orders (I(+1) and I(-1)) were utilized.
• These orders' amplitudes are proportional to right and left circular polarization components.
• Unpolarized white light and the grating's spectral selectivity were exploited.

Main Results:

• The proposed method successfully suppresses artifacts from anisotropic samples and nonideal optics.
• True CD spectra were evaluated in parallel within the spectral range of interest.
• The method demonstrated real-time measurement capabilities.

Conclusions:

• The developed technique offers a robust and simple approach for real-time CD spectroscopy.
• This method enhances accuracy by mitigating common sources of error in CD measurements.
• It provides a valuable tool for spectral analysis where precise CD data is required.