Under the same laser energy condition, the energy density or power density of the laser beams with different spots is different so that the laser energy required for cleaning can be conveniently controlled. The laser can achieve a high degree of concentration in time and space. Laser cleaning uses these characteristics to remove contaminants and effectively repair cultural relics.
Internationally, laser cultural relic cleaning and protection technology have been widely used to clean and protect museum cultural relics and buildings. Many examples have proved that laser cleaning is an effective method for cultural antiques and paintings.
Infrared lasers have a long wavelength and low single-photon energy, which cannot achieve the effect of removing surface contaminants. Increasing the laser power will cause burns to the painting substrate. Therefore, in the cleaning and protection of paintings, the shorter wavelength visible light or ultraviolet laser is generally used for cleaning and protection.
Among Western paintings, oil paintings are mainly used. The surface of most oil paintings is attached with a layer of varnish with a thickness of 0.05 to 0.08 mm. Protect the surface of the oil painting while improving the color. However, the varnish layer on the surface is prone to aging due to aggregation and actinic action, forming a black, strong film layer. In addition, external pollutants such as dust will have a particular impact on the original color of the painting and cause the visual distortion of the picture.
Traditional mechanical and chemical cleaning may cause material damage on the surface of the painting or chemical damage to the paint. Thereby it caused irreparable damage to the paintings and artworks. Compared with these traditional methods, laser cleaning protection technology has higher energy and controllability of the action position. Because of the high point of single-photon, the ultraviolet laser uses the photolysis effect to destroy or weaken the ablation between pollutants and achieve the purpose of cleaning.
Laser cleaning technology can gently clean and remove soil on sandstone, marble, granite, terracotta, and concrete without causing physical damage or damage to the building surface. The laser can finely clean the surface with colors or pigments, remove the accumulated smoke, dust, and unsightly soil to restore the original beautiful appearance. The laser power (0-100%) and intensity in the system can be adjusted highly precisely, which provides a unique and advantageous tool for the restoration of cultural relics.
