Colóquio 30/06/2023: A High-throughput multimodal wide-field Fourier-transform Raman microscope

Raman microscopy is a powerful analytical technique for materials and life sciences that enables mapping the spatial distribution of the chemical composition of a sample. State-of-the-art Raman microscopes, based on point-scanning frequency-domain detection, have long (∼1 s) pixel dwell times, making it challenging to acquire images of a significant area (e.g., 100 × 100 μm).
In this talk we will present an innovative compact wide-field Raman microscope based on a time-domain Fourier-transform approach, entirely developed at CNR and Politecnico di Milano (Italy). The novel system enables parallel acquisition of the Raman spectra on all pixels of a 2D detector. To this aim, we developed a common-path birefringent interferometer, which provides exceptional delay stability and reproducibility, and can rapidly acquire Raman maps (∼30 min for a 250 000 pixel image) with high spatial (<1 μm) and spectral (∼23 cm-1) resolutions.
We will explore how time-domain detection offers the unique advantage of disentangling fluorescence and Raman signals, which can both be measured separately. We validate the system by Raman imaging plastic microbeads and demonstrate its multimodal operation by capturing fluorescence and Raman maps of a multilayer-WSe2 sample, providing complementary information on the strain and number of layers of the material.