Fig. 1. Principle of confocal LIBS imaging system

Fig. 2. Axial response curve for confocal LIBS imaging system

Fig. 3. Influence of pinhole size on the spatial resolution of confocal microscope. (a) Influence of pinhole size on FWHM and signal intensity of confocal lateral response curve; (b) influence of pinhole size on FWHM and signal intensity of confocal axial response curve

Fig. 4. LIBS spectrum collection module. (a) Collection light path of LIBS signals; (b) entrance of the collection fiber

Fig. 5. Confocal LIBS imaging system

Fig. 6. Spatial resolution experimental results. (a) Axial focusing ability; (b) spatial resolution

Fig. 7. Relationship between spatial resolution and LIBS intensity. (a) Ablation craters under different energy pulse lasers; (b) ablation craters' diameter, depth, volume and LIBS intensity under different energy pulse lasers; (c) ablation craters by pulse laser at different defocus distances; (d) ablation craters' diameter, depth, volume and LIBS intensity by pulsed laser at different defocus distances

Fig. 8. Agate ore sample. (a) White light image of the tested sample; (b) LIBS spectrum of the tested sample (480-600 nm)

Fig. 9. 3D fusion maps. (a)CCD image; (b)-(f) 3D maps of Ba, Ti, Ca, Cu, Fe

Fig. 10. Results of pulsed energy

Fig. 11. Results of laser focusing

Fig. 12. Results of pulsed energy

Table 1. Parameters of three different types of plano-convex quartz lensesunit: mm

Table 2. RMS radius of the focus spot for three different types of plano-convex lensesunit: μm