The pulsed Nd:YAG laser cleaning process relies on the characteristics of the light pulses produced by the laser, based on high intensity beams, short pulses.
Photophysical reactions caused by interactions between laser and contaminated layers. Its physical principles can be summarized as follows:
1) The beam emitted by the laser is absorbed by the contaminated layer on the surface to be treated.
2) Absorption of large energy forms a rapidly expanding plasma (a highly ionized unstable gas) that generates a shock wave.
3) The shock wave causes the contaminants to become fragments and is rejected.
4) The light pulse width must be short enough to avoid heat buildup that would damage the surface being treated.
5) Experiments have shown that when there is an oxide on the surface of the metal, the plasma is generated on the metal surface.
The plasma is generated only when the energy density is above a threshold, which depends on the contaminated or oxide layer being removed. This threshold
The effect is important for effective cleaning while ensuring the safety of the substrate material. There is also a second threshold for the presence of plasma. If possible
When the amount density exceeds this threshold, the substrate material will be destroyed. In order to ensure effective cleaning of the substrate material, it must be based on
The laser parameters are adjusted such that the energy density of the light pulse is strictly between two thresholds.
Each laser pulse removes a certain thickness of the contaminated layer. If the contaminated layer is thick, multiple pulses are required for cleaning. Dry the surface
The amount of pulse required for netting depends on the degree of surface contamination. An important result produced by the two thresholds is the self-control of cleaning. High energy density
Light pulses at the first threshold will always reject contaminants until the substrate material is reached. However, because its energy density is lower than that of the substrate material
The threshold is destroyed so the substrate is not damaged.