Acta Photonica Sinica, Volume. 50, Issue 7, 249(2021)
Laser Cleaning Process Monitoring of Metal Surface Based on Image Processing and LIPS Analysis
Figures & Tables(11)
Fig. 1. Photo of rust layer on steel plate sample. The illustration shows the 200 times optical micrograph of the rust layer section
Fig. 2. Schematic of on-line monitoring system for laser cleaning. The illustrations are the 2D distribution of beam energy and the path diagram of laser cleaning
Fig. 3. Variation between the number of cleaning and the rust cleaning rate at different overlap ratios
Fig. 4. Macro and micro images of the steel plate sample surface after laser cleaning
Fig. 5. Variation between the number of cleaning and LIBS at different rust layer and corresponding correlation coefficient
Fig. 6. Flow chart of laser cleaning process monitoring based on the cooperation of image processing and LIPS analysis
Fig. 7. Macro photos， micro 3D， 2D topography images of the steel plate sample surface before and after laser cleaning based on the process monitoring method
Table 1. Performance parameters of laser cleaning system
View tableView in ArticleTable 1. Performance parameters of laser cleaning system
Parameter Value Wavelength/nm 1 064 Laser average power/W 100 Laser pulse energy/mJ 1 Pulse width/ns 200 Maximum scanning speed/（mm·s-1） 9 000 Repetition frequency/kHz 100 Focused spot diameter/µm 100 Laser beam quality factor M2 < 2.0
Table 2. EDS analysis of four different color areas
View tableView in ArticleTable 2. EDS analysis of four different color areas
C/（wt%） O/（wt%） Fe/（wt%） Rust layer 1.15 22.51 76.34 Substrate 1.15 0.84 98.01 Argent area 1.15 1.08 97.77 Yellow area 1.14 2.63 96.23 Blue area 1.14 6.47 92.39 Red & black area 1.15 14.31 84.54
Table 3. Characteristic spectral lines of steel substrate in LIPS
View tableView in ArticleTable 3. Characteristic spectral lines of steel substrate in LIPS
Atom Number of cleaning Observed wavelength/nm Standard wavelength/nm FeⅠ
FeⅠ
FeⅠ
FeⅠ
FeⅠ
1
2
3
4
5
356.62
358.47
373.34
382.11
404.58
419.90
430.78
432.55
438.34
440.45
356.630
358.478
373.332
382.119
404.581
419.909
430.79
432.576
438.354
440.475
FeⅠ
FeⅠ
FeⅠ
FeⅠ
FeⅠ
6
7
8
9
10
Table 4. Data comparison between single monitoring and cooperative monitoring after laser cleaning
View tableView in ArticleTable 4. Data comparison between single monitoring and cooperative monitoring after laser cleaning
Item Image processing LIPS analysis Cooperative monitoring Area of monitoring Big Small Big Correcting the number of cleaning No Yes Yes Controlling process No Yes Yes Cleaning rate η < 93% / > 98% Oxygen content 1.08%~14.34% 0.99%~1.17% 0.88%~1.15% γ value / > 0.98 > 0.98
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Rongwei ZHA, Lidong YU, Ben LI, Yang BAI. Laser Cleaning Process Monitoring of Metal Surface Based on Image Processing and LIPS Analysis[J]. Acta Photonica Sinica, 2021, 50(7): 249
Paper Information
Category: Lasers and Laser Optics
Received: Dec. 18, 2020
Accepted: Feb. 5, 2021
Published Online: Sep. 1, 2021
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