Wide-field spectroscopic imaging of optical activity

Abstract

Optical activity spectroscopy techniques, such as circular dichroism and optical rotatory dispersion, are essential for investigating the chiral properties of molecules and materials. However, current methods often struggle to analyse heterogeneous and spatially varying chiral samples. On one hand, spectroscopic approaches, although sensitive, often require large sample volumes and produce ensemble-averaged data. On the other hand, chiral imaging delivers spatial resolution at the expense of time-consuming confocal scanning and complex instrumentation. Addressing this gap, we introduce a platform for wide-field, spectrally resolved optical activity imaging. Using polarization-sensitive off-axis holography to simultaneously capture left- and right-circularly polarized components, our system allows the single-shot retrieval of circular dichroism and optical rotatory dispersion images, as well as eliminating artefacts caused by linear anisotropies. Our results are not only consistent with traditional circular dichroism spectroscopy but also demonstrate the ability to spatially resolve local chirality variations lost by ensemble averaging, including enantiomeric excess. This platform holds great promise for analysing complex biological and material samples, expanding the scope of chiral characterization.