Latech Precision Electronic Technology Co., Ltd.
Laser cutting is familiar to everyone. Do you know the technology of laser rust removal? Laser rust removal technology, it is amazing, laser swept rusty iron, instant rust disappeared...
The principle of laser rust removal is laser cleaning.
The cleaning process of pulsed Nd:YAG laser depends on the characteristics of the optical pulse generated by the laser, and is based on the photophysical reaction caused by the interaction of high intensity beam, short pulse laser and the contaminated layer. Its physical principles can be summarized as follows:
A) The beam emitted by the laser is absorbed by the contaminated layer on the surface to be treated.
B) The absorption of large energy forms a rapidly expanding plasma (highly ionized unstable gas), which produces shock waves.
C) Shock waves cause pollutants to become debris and be removed.
D) The width of the optical pulse must be short enough to avoid the thermal accumulation of the damaged surface.
E) Experiments show that when there are oxides on the metal surface, plasma is generated on the metal surface.
The plasma is produced only when the energy density is higher than the threshold, which depends on the removal of the contaminated layer or oxide layer. This threshold effect is very important for effective cleaning under the condition of ensuring the safety of the substrate material. There is a second threshold for the appearance of plasma. If the energy density exceeds this threshold, the substrate material will be destroyed. In order to clean the substrate effectively, the laser parameters must be adjusted according to the situation, so that the energy density of the optical pulse is between two thresholds strictly.
Each laser pulse removes a certain thickness of contaminated layer. If the contamination layer is thicker, multiple pulses are needed to clean it. The number of pulses needed to clean the surface depends on the degree of surface contamination. An important result of the two thresholds is the self-control of cleaning. Optical pulses with energy density higher than the first threshold will remove pollutants until they reach the substrate material. However, because its energy density is lower than the damage threshold of the substrate material, the substrate will not be destroyed.