In order to remove the black pollution crusts on the marble artifacts, picosecond (ps) laser cleaning of marble samples has been performed experimentally at three different wavelengths (1064 nm, 532 nm, and 355 nm). Ablation threshold and cleaning efficiency of the three wavelength lasers have been characterized by measuring monolayer ablation depth with 3D microscope using the blow-off model. It has been found that laser ablation efficiency at 1064 nm wavelength is the highest among the above three wavelengths, while that of 355 nm wavelength is the lowest. The ablation threshold of 1064 nm, 532 nm, and 355 nm laser pulses are 0.198±0.033 J/cm2, 0.573±0.114 J/cm2 and 0.739±0.249 J/cm2 respectively. The advantages and effectiveness of ps laser cleaning have been demonstrated in removing contaminants on the marble samples at three different wavelengths, especially at 1064 nm.
Laser cleaning of manmade contaminants from stone samples have been performed experimentally using picosecond (ps) and nanosecond (ns) laser pulses. Regarding the surface roughness after laser cleaning, optimal cleaning parameters using ps laser have been obtained. Discoloration effect induced by ns laser cleaning of stone sample is improved with the usage of ps laser. The comparison on the roughness and elemental analysis of the cleaned area in the experiment also demonstrates the advantages and effectiveness of ps laser cleaning of stone samples.
Bronze cultural relics are an important part of Chinese traditional historical and cultural heritage. With the rapid development of ultrafast lasers in recent years, picosecond lasers have gradually been used in laser precision processing due to their controllability, reliability and low cost. With the increase of laser power, the laser ablation effect will occur[1].The contaminant on the surface of bronze cultural relics are thinner compared to that on other type of cultural heritage and need more accurate cleaning method needs to be used for removing contaminants without damaging the substrate of bronze relics. In 2013, Zhang Xiaotong et al. used wet laser cleaning technology to perform laser cleaning on the gilt bronze statues provided by Hebei Cultural Protection Center. They changed the power density, conducted preliminary trials of bronze cleaning [2]. In 2018, Shen Yijia et al. used agar gel and laser combined method to protect the bronze cultural relics from laser damage[3].
The ceramics is easily broken due to various reasons. These reasons include unearthed excavation, careless operation and so on. When the ceramics is broken in pieces, the antique restorers take advantage of the adhesive to stick these fragments together to exhibit the beauty of original cultural relics. Therefore, the removal of adhesives such as adhesives on the cross-section of ceramic samples is a very important link in the restoration and protection of cultural relics and has important significance. In ancient times, the way of restoring these ceramics is so inappropriate and unreasonable that the adhesive is left among the cross section of these pieces. It becomes a problem for the following antique restorers. In order to solve this problem, we select a piece of the ceramics that possess above characteristics by utilizing laser to clean the left adhesive on the cross section tentatively. To better explore the optimized cleaning parameters relatively, we have made standard samples of adhesive to get better cleaning effect. These results will provide the reference value to our following study.
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