(A) Schematic of the hand-held BLS probe (PBS = Polarizing Beam Splitter; λ/4 = quarter waveplate; λ/2 = half waveplate; IP = intermediate image plane; L1 & L2 relay lenses; L3 focusing lens; q = predominant phonon-scattering wavevector probed in the sample). Inset shows a sketch of the multimode fiber bundle cross section used for coupling light into and out of the probe, and the excitation pattern projected onto sample (green dots). Scale bar = 1 mm. (B) Photograph of hand-held probe. (C) Example of BLS-spectra showing Stokes (S) and Anti-Stokes (AS) BLS scattering peaks shifted by frequencies ±ν_B relative to the probing laser frequency ν₀. Also shown is an example of a raw spectral projection measured with the BLS imaging spectrometer using the hand-held probe (dashed line = dispersion axis). (D) BLS measurements on the same samples as in Figure 1 using the hand-held probe (x). Also shown are mean values (□) and the standard deviation of the mean (grey bars) of the confocal scan measurements (viz. Fig. 1 and Table 1). Inset: Mean ν_B obtained from confocal scan measurements versus that obtained using the hand-held probe (later is average of 5 measurements). Statistical differences are for ν_B of the different tissues measured using the hand-held probe, and were performed using unpaired t-test’s with Welch’s correction (*p < 0.05, ****p < 0.0001). Sample acronyms are as defined in Table 1.