Fig. 1. Experimental setup of micro hole sprayer assisted LIBS

Fig. 2. Picture and schematic of micro hole sprayer

Fig. 3. LIBS spectrum of calcium element

Fig. 4. LIBS spectrum intensities at different pore sizes and data processing methods

Fig. 5. Changes of LIBS spectrum RSD with different pulse number

Fig. 6. Relationship between LIBS spectrum intensity or RSD and laser energy

Fig. 7. Boltzmann plot of calcium element

Fig. 8. Hα 656 nm spectral line and Lorentz fitting curve

Fig. 9. Fitting curve of calcium element

Fig. 10. Linear fitting curve of samples with 20 concentrations

Fig. 11. Linear fitting curve of sample with eight mass concentrations

Fig. 12. Bar chart of sample mass concentration comparison

Fig. 13. Spectrum of offshore seawater in Qingdao

Fig. 14. Continuous detection result of calcium element

Fig. 15. Estimated and actual concentrations of calcium element