I am service for Central-Laser company. Today, I would like to share some basic information about the laser clean machine. Please help me to update and rich this information, if you know more about it. Thank you in advance. www.central-laser.com
First of all, we need to know about the nature of the laser. In simple terms, a laser is no different from the shadow-following light (visible and invisible light) around us, except that the laser relies on a resonator to concentrate light in the same direction, and has pure wavelength with better coordination, so theoretically all wavelengths of light can be used to form Laser, however, is actually limited by the media that can aroused, so the light source that can produce lasers with stable and suitable for industrial production is rather limited
The most widely used lasers are probably Nd: YAG lasers, CO2 lasers, and excimer lasers. Nd: YAG laser can be transmitted through the optical fiber and is more suitable for industrial applications, so it is often used in laser cleaning.
For example, when sub-micron contaminated particles adhere to the surface of the workpiece, they tend to stick very tightly. Common cleaning methods cannot remove them, but it is very effective to clean them by nano-laser irradiation. Because the laser is non-contact cleaning for the workpiece, it is very safe to clean the precision workpiece or its fine parts, so the precision can be ensured. So laser cleaning has unique advantages in the cleaning industry.
The working principle of laser cleaning machine is:
The process of pulsed Nd: YAG laser cleaning depends on the characteristics of laser pulses, which are based on the photophysical reactions caused by the interaction of high-intensity beams, short pulses, and contaminated layers.
1. The beam emitted by the laser is absorbed by the pollution layer on the surface of the workpiece.
2. The absorption of large energy forms a rapidly expanding plasma (highly ionized unstable gas), which produces shock waves.
3. Shock waves turn pollutants into fragments and are eliminated.
4. The laser pulse width must be short enough to avoid the thermal accumulation of the surface treated.
5. Experiments show that when there are oxides on the surface of the metal, the plasma occurs on the metal surface.
Plasma is produced only when the energy density is higher than the threshold value, which depends on the removal of contaminated or oxidized layer. This threshold effect is very important for effective cleaning under the condition of ensuring the safety of substrate materials. There are second thresholds for the emergence of plasma.
If the energy density exceeds this threshold, the base material will be destroyed. In order to keep the substrate material safe and clean effectively, the laser parameters must be adjusted according to the situation, so that the energy density of the laser pulse is strictly between two thresholds.
Each laser pulse removes a certain thickness of the fouling layer. If the pollution layer is thicker, multiple pulses need to be cleaned. The amount of pulse needed to clean the surface depends on the degree of surface contamination.
An important consequence of the two thresholds is the self-control of cleaning. Laser pulses with energy densities higher than the first threshold will remove contaminants until they reach the substrate material.
However, because the energy density of the substrate is lower than that of the substrate material, the substrate material will not be damaged.
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