Fig. 3.

(a) Raman spectra of P1 (polystyrene beads, 30 µm diameter) and P2 (methyl methacrylate beads, 20 µm diameter) with the superimposed designed binary filters (Raman photons falling in the white stripes are kept while the photons falling in the grey stripes are rejected), (b) sample seen from a microscope camera. (c) projection map of the two different spectral filters from the image seen in (b) where the exposure time is 250 µs/pix/filter. (d) Classification map after applying the algorithm, described in (Réfrégier et al., 2019), on the filtered measurements shown in (c). For each image, the scale bar is 30 µm and the FOV is 100 µm $\times$ 100 µm (100 pixels $\times$ 100 pixels).