Any object can reflect light, which is why we can see things. For the lens, in order to allow light to pass through the lens completely, it is better for the lens to fully reflect the real situation of nature on the film. High quality optical glass, its light transmittance can reach above 90%, still remaining light loss needs to be coated on the lens surface to compensate. Therefore, the optical lens is mainly coated with the anti-reflection film also known as the permeability film. In order to meet all kinds of requirements, it is often necessary to plating multilayer film. To improve the glass’s resistance to scratches, the outermost layer is often a film of high hardness.In the laboratory, modern technology can pass almost 100 percent of the light. This is because in practical use, the lens is more or less affected by dust, dirt, and so on, so that the light through the lens is reduced. There are many methods of coating, but the conventional methods are only a few.
1. Chemical methods, including sol-gel method, chemical vapor deposition, etc.According to the properties of the membrane, a solution of certain components is prepared, and then:
- Immersion plating: Heat the clean glass to a certain temperature, put it into a prepared chemical solution, remove and dry. This is obviously a double mask.
- Plating: Place the prepared membrane solution on the spray gun and spray it on the clean, hot glass surface. Drying.The vitreous body may be moving or rotating to increase the uniformity of the membrane. May be plated on both sides or one side. (in the past, the so-called slagging method was used for lens coating, but due to uneconomical, inorganic film plating has been out of use in modern technology, but it is still a common and low-cost method for organic film plating.)
2. Physical coating: There are vacuum evaporation, ion plating, sputtering coating (can be attributed to physical vapor deposition) and other different forms. More used in metal coating, reflective film, etc.As a mirror. Generally, the coating strength of chemical method is lower than that of physical method, but with the rapid development of coating technology, especially in the recent one or two decades, the effect achieved by chemical or physical method is no different. It’s just a cost difference.Previously, only one layer of film can be plated by chemical method, and the upper layer is usually damaged due to the influence of temperature when the second layer is plated, but modern technology has basically solved this problem.