Real-Time Circular Dichroism Spectrograph Based on a Single Liquid Crystal Diffractive Element

A simple spectrograph based on a polarization grating has been developed for real time measurements of circular dichroism. The main and unique element is a liquid crystal replica of a polarization grating recorded by means of holographic techniques in thin films of organic materials. This gratings offer long time stability and high diffraction efficiency. Due to the peculiar features of the grating, the circular dichroism of any system can be easily evaluated measuring only the intensities of the first order diffracted beams, just locating the grating after the investigated system. The spectral selectivity of the grating allows simultaneous measurements for all wavelengths of the spectra by using two linear Charged-Coupled devices.