Hyperspectral stimulated Raman scattering (hSRS) imaging for mapping three types of polymer beads with overlapping but distinct Raman spectra (A) Spontaneous Raman spectra of the three polymer beads. The black solid line indicates overlapping Raman spectra at 3028 cm-1 (B) stimulated Raman scattering (SRS) imaging of the three polymer beads at 3028 cm-1 with different color arrows pointing out corresponding beads (C) SRS spectra for the three polymer beads pointed out by the arrows (in B). (D) Color-code distribution of the three polymer beads generated using hSRS imaging coupled with spectral decomposition. PMMA: Poly (methyl methacrylate). Reprinted with permission from D. Fu, G. Holtom, C. Freudiger, X. Zhang and X. S. Xie, J. Phys. Chem. B, 2013, 117, 4634–4640 Copyright (2018) American Chemical Society.