Fig. 1. Schematic diagram and serial number of laser paint remove sample
(a): Paint remove sample of different layers; (b): Paint remove sample of different thickness

Fig. 2. System diagram for on-line detection of LIBS

Fig. 3. LIBS spectra
(a): Before filtering; (b): After filtering; (c): After filtering of air

Fig. 4. Morphology and energy dispersive spectroscopy (EDS) images of paint surface
(a): SEM of Tc-C; (b): SEM of Pr; (c): EDS of Tc; (d): EDS of Pr

Fig. 5. LIBS spectra
(a): Top coating; (b): Top coat removing(Partially); (c): Top coat removing(Completely); (d): Primer; (e): Primer removing(Partially); (f): Primer removing(Completely)

Fig. 6. The LIBS spectra peak intensity changes of the characteristic elements of topcoat and primer in the process of layered laser paint remove

Fig. 7. LIBS spectra
(a): Primer; (b): Primer removing (5 μm); (c): Primer removing (10 μm); (d): Primer removing (15 μm); (e): Primer removing (20 μm); (f): Primer removing (35 μm)

Fig. 8. LIBS spectra of single primer at different laser pulse

Fig. 9. LIBS spectra of Ti, Ca and Al elements irradiated by different laser pulse numbers
(a): Ti Ⅰ; (b): Ca Ⅱ; (c): Ca Ⅰ; (d): Al Ⅰ