A multimodal widefield hyperspectral microscope.

Fluorescence and Raman spectroscopy are complementary methods for investigating the properties of materials since they address different transitions of molecules. However, due to the huge difference in the typical cross-sections of the two effects, fluorescence has been always considered a hindrance for Raman, and no combined instrument exists. In addition, typical Raman microscopes rely on point-by-point scanning and dispersive spectrometers: this results in long acquisition times ($\sim 5 h$ for $0.1 {MP}$ images), which can be reduced only by sacrificing the spatial resolution. We have developed an innovative Fourier-transform hyperspectral microscope capable of disentangling Raman and fluorescence signals only by changing the sampling approaches. The microscope is based on an ultrastable and compact common path interferometer that enables multimodal high-throughput, widefield imaging, greatly reducing the acquisition time. Our hyperspectral microscope is capable of performing sequentially high-spatial resolution ($<1 \mu m)$ Raman mapping and spectrally resolved fluorescence imaging in $\sim$ 30 min for $0.1 {MP}$ image. The details of the instrument and applications will be presented.