Fig. 1. Relationship between linear chirp parameters and glass rod length. (a) Change of chirp when glass rod length is 1-15 cm; (b) change of chirp when glass rod length is 10-13 cm

Fig. 2. Overall design scheme of spectral focusing cars microscopic imaging system

Fig. 3. Melamine CARS microscopic imaging results under different conditions. (a) Melamine CARS microscopic imaging results under time coincidence; (b) shift pump pulse imaging results; (c) shift Stokes pulse imaging results; (d) non-time zero imaging results

Fig. 4. Microscopic imaging and Gaussian fitting curve of melamine CARS. (a) Microscopic imaging of melamine CARS; (b) Gaussian fitting curve of CARS signal in A region

Fig. 5. Melamine CARs microscopic imaging results under different rotation angles of half wave plate in the pump light. (a)-(e) Imaging results corresponding to rotation angles of 0°, 20°, 40°, 60°, and 80°; (f) imaging result of maximum inhibition of non-resonant background; (g) resonance signal, non-resonant background, and ratio changes of resonance signal to non-resonant signal

Fig. 6. Melamine CARS microscopic imaging results under different rotation angles of half wave plate in Stokes light. (a)(b) Imaging results corresponding to rotation angles of 20° and 70°; (c) imaging result of maximum inhibition of non-resonant background; (d) resonance signal, non-resonant background and ratio changes of resonance signal to non-resonant signal