Fig. 1. Schematic of the spectral focusing CARS microscope imaging system

Fig. 2. Total output spectrum of femtosecond laser oscillator and reflection/transmission of DM

Fig. 3. Signal contrast diagram. (a) Multiply frequency signal; (b) sum frequency signal

Fig. 4. CARS microscopic imaging results. (a) Image of the polystyrene powder sample in the field of view of the eyepiece; (b)-(g) CARS microscopic imaging results of sample in the red frame range with pump-Stokes delays of 100, 320, 540, 660, 900, and 1200 fs

Fig. 5. Comparison results. (a) Spectral focusing CARS signal intensity spectrum of polystyrene; (b) Raman spectrum of polystyrene

Fig. 6. Gaussian fitting result. (a) CARS microscopic imaging of polystyrene; (b) Gaussian fitting curve of CARS signal in region A

Fig. 7. CARS microscopic imaging results. (a) Image of the polystyrene powder sample in the field of view of the eyepiece; (b)-(g) results of CARS microscopic imaging at the positions of 0, 4, 7, 10, 13, 16 μm obtained by Z-axis scanning

Fig. 8. Three-dimensional imaging results. (a) 3D reconstruction of nearly triangular polystyrene powder; (b) top view of 3D reconstruction