Fig. 5
From: A framework for spontaneous Brillouin noise: unveiling fundamental limits in Brillouin metrology
Implementation of the proposed framework to evaluate the performance of Brillouin imaging and microscopy. a Experimental setup. Obj: objective; QWP: quarter-wave plate; S: optical shutter; PBS: polarizing beam splitter; HWP: half-wave plate. b SNR vs. pump power for two samples: a fiber (Brillouin imaging) and double-distilled water (Brillouin microscopy). For the fiber, pump power ranges from −20.8 to 13.2 dBm with 50 kHz system bandwidth; for water, from -4 to 17 dBm with 50 Hz bandwidth. Water sample preparation follows the method described in panel a, sample (ii). c Brillouin imaging of a fiber sample: brightfield, Brillouin shift, and linewidth images under different pump powers. Scale bars are 40 μm (brightfield) and 2 μm (Brillouin). Colorbars show Brillouin shift (\({\varOmega }_{{\rm{B}}}/2{\rm{\pi }}\), see Supplementary Fig. S10 for a detailed analysis) and linewidth (\({\varGamma }_{{\rm{B}}}/2{\rm{\pi }}\)). White and gray regions of interest (ROIs) indicate regions with high Brillouin amplitude (see Supplementary Fig. S11), with overlaid text showing fitting precision for each. d (i) Brillouin microscopy of a phantom bead in agarose: brightfield, Brillouin shift, and linewidth images under varying pump powers. Scale bars: 5 μm. White ROI corresponds to agarose; gray ROI highlights part of the bead. d (ii) Brillouin microscopy of a HeLa cell: similar format and power range. Scale bars: 10 μm. White ROI marks culture medium around the HeLa cell
