Laser is one of the major inventions of the natural sciences of the twentieth century. In 1960, the first laser was produced in the world. Subsequently, lasers with good coherence, small enemy angles, and high energy concentration have been widely used in various fields, such as laser ranging, laser processing, and laser communication. In the early 1980s, people began to use high-energy laser beams to illuminate the surface of the workpiece, causing the surface of the dirt, rust or coating to instantaneously evaporate or peel off, and effectively remove the attachment or coating on the surface of the object at high speed. The process of cleaning the surface of the material is laser cleaning. Since the past ten years, laser cleaning has moved from the laboratory to practical applications, used in various rubber product molds, silicone products molds to remove oil, rust, cultural relics, microelectronic circuit boards and other materials cleaning, and achieved very Good economic and social benefits.
In the mid-1980s, in order to meet the needs of industrial production to remove tiny particles on memory templates, laser cleaning has received extensive attention and research and was officially recognized as an effective cleaning method that researchers have tried to use. Conventional cleaning methods such as mechanical cleaning, chemical cleaning, and ultrasonic cleaning to remove submicron particles attached to the template are less than ideal. Since the adsorption force of the particles on the template (van der Waals force, electrostatic force, etc.) is quite amazing, such as particles of 1 μm size, its adsorption force on the surface of the template is about 106 times that of its gravity, and the mechanical cleaning method cannot be completed. The removal of tiny particles, chemical cleaning can lead to corrosion and recontamination of the template. Ultrasonic cleaning requires the template to be placed in the center of the sonic vibration, which will cause the template to rupture. Laser cleaning is produced under such circumstances. In this case, people began to systematically study it: its appearance has solved the problem of contamination on the surface of the template, and with the development of laser cleaning technology, It has also been widely used in many other fields.
In the late 1980s, scientists found that covering the surface of the substrate with a liquid auxiliary layer was more conducive to the removal of contaminating particles. Among them, water is such an effective auxiliary layer. The method of covering the surface of the article to be cleaned with a liquid film having a thickness of the order of millimeters and then irradiating with a laser to remove the contaminated particles is what we later call the steam (wet) laser cleaning, compared with the dry type. Laser cleaning, steam laser cleaning has higher cleaning efficiency. It was not until the early 1990s that laser cleaning really entered industrial production. In fact, almost in 1987, three research groups independently discovered the effects of laser cleaning. Among them, the research team led by Zapka obtained the first patent on laser cleaning and recognized its application prospects in industry. Another research group is the Max Planck Institute for Biochemistry and Physics in Toku, scientists The silicon template was covered with gold particles having a size of 35 nm, and then the nitrogen molecular laser was directly irradiated onto the solid surface, and as a result, the gold particles on the surface were successfully removed, while the silicon template was not damaged, indicating that the laser was used to clean the solid surface. Contaminated particles are feasible.
In 2001, Fourrier and its collaborators performed steam laser cleaning experiments on particles of different shapes, sizes, and materials to find the laser intensity required for different particles in the range of tens to hundreds of nanometers. The threshold is the same. This “widely consistent threshold” provides a more favorable support for industrial use of steam laser cleaning to remove sub-micron particles. Although the development of laser cleaning is based on the cleaning of small solid particles on the surface, research on other applications has been carried out accordingly. For example, in the 1970s, after research and experimentation, it was found that lasers are cleaning historical buildings and artworks. There is feasibility. In 1992, UNESCO successfully used laser cleaning to repair the Yasmin Cathedral in England. Some countries in Europe have also laser cleaned the Amiens Cathedral (France), St. Stephan’s Cathedral (Vienna, Austria), the Tomb of the Unknown Soldier (Warsaw, Poland). The application of laser in stripping has also attracted the attention of researchers. Woodroffe et al. in the United States have done a lot of work in this area.
In the 1990s, researchers in Germany and Japan developed high-power TEA-CO2 lasers for laser paint stripping, and used them to do a series of experiments. It was not until 2005 that researchers published papers on the stripping of aircraft using high-power TEA-CO2 lasers. Scientists from various countries have also made a lot of exploratory research on the application of tire molds, surface treatment, space garbage and other aspects, and achieved remarkable results.