Fig. 1. Scheme of the PARS setup. CIR, circulator; COL, collimator; DM, dichroic mirror; BS, beam splitter; OL, objective lens; CCD, charge-coupled device; C/L, C/L band filter; PD, photodiode; DC, DC block; AMP, amplifier.

Fig. 2. Imaging results of carbon fibers. (a) PARS image of carbon fiber networks. (b) Typical PARS signal of a single carbon fiber in the time domain. (c) Lateral resolution of the PARS system by scanning a carbon fiber, resulting in an FWHM of 1.62μm. (d) Axial resolution of the system by an A-scan of a carbon fiber, with an FWHM of 30.25μm.

Fig. 3. PARS images of phantom samples. (a) PARS image of a droplet of olive oil. (b) PARS image of solid butter with a specific branch-like pattern. (c) PARS signals of oil and butter in the time domain. (d) frequency responses of the PARS signals.

Fig. 4. PARS images of biological samples. (a) PARS image of the unlabeled C. Elegans. The right upper corner figure is the sample under bright-field microscopy. The yellow window shows the enlarged image with a smaller step size, which is displayed as (b). (c) PARS image of the mouse brain slice, of which the white window shows high contrasts of the tissue.