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Fabrication and coating of glass lenses
- Aug 13, 2018 -

Method for manufacturing glass lens

1. Previous methods: The melted optical glass was made into a glass rod with a slightly larger diameter and the lens to be processed during the molding process, and then cut into sheets according to the thickness of the lens. Get special mechanical processing equipment, according to requirements processed into finished products. The main processes are rough grinding, middle grinding, fine grinding, fine grinding, polishing and annealing. Coarse grind to fine grinding materials are mainly different kinds of granularity. The polishing method can be polished by flame when the requirement is not high. Advanced lenses must be mechanically polished with cerium oxide.

2, the current method is to use the mold hot pressing. Mainly in order to reduce the waste in the original method and improve work efficiency. The method is: according to the quality of the lens to determine the quality of the melted glass, the glass in a certain temperature, viscosity state into the mold, pressing molding, and finally annealing. There are two kinds of results.

First, the quality requirement can be achieved once the product is in place.  Tiny defects can be made up by coating. The requirement for mold is very high. As far as I know, it is not yet available in China. This product can meet most of the needs. The accuracy of the lens is mainly affected by the accuracy of the die. Secondly, the product is a high precision blank, and then according to the above original method of machining, but the amount of processing is very small, can significantly improve production efficiency.  This method is often used for products with high precision. The accuracy of lens is mainly affected by the accuracy of machining instruments.


Two. Basic knowledge of coating

As we all know, any object can reflect light, which is why we can see things. For lenses, in order for light to penetrate the lens completely, it is best for the lens to penetrate all kinds of light completely, reflecting the true nature of the film. High quality optical glass, its light transmittance can reach more than 90%, the remaining light loss needs to be made up by coating the lens surface. Therefore, on the optical lens is mainly antireflective film, also known as antireflection coating. In order to meet all kinds of requirements, multilayer coatings are often needed. In order to improve the scratch resistance of glass, the outer layer is often the film with high hardness. In the laboratory, modern technology almost achieves the adoption of light one hundred percent. The reason for this is that in actual use, the lens will be more or less affected by dust, dirt, and so on, making less light through the lens. There are many methods of coating, but there are several conventional methods.

(1) chemical methods, including sol-gel method and chemical vapor deposition. According to the properties of the membrane, a certain component of the solution is prepared.

1. Immersion plating. The clean glass is heated to a certain temperature, then put into a well-prepared chemical solution, taken out, and dried. This membrane is obviously a double-sided membrane.

2, spray coating. Install the membrane solution on the spray gun and spray it onto the clean, hot glass surface. Dry. The vitreous body can be moved or rotated to increase the uniformity of the film. It can be plated with double-sided or single side. (In the past, the so-called glue-throwing method was used for lens coating, but because of its ineconomic nature, inorganic coatings have been eliminated by modern technology, but it is still a common, low-cost method for organic coatings.)

(two) physical coating. There are vacuum evaporation, ion plating, sputtering coating (all can be attributed to physical vapor deposition) and many other different forms. It is mainly used for metallized film, reflective film, etc. Like a mirror. Generally, the coating strength of chemical method is generally 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 methods is no longer different. It's just a cost difference. Previously, only one layer of film could be deposited by chemical method. When the second layer was deposited, the upper layer would be destroyed because of the influence of temperature. But modern technology has basically solved this problem.


Three, clean the membrane. The outermost layer of the membrane is usually a hard film, general hand touch or washing will not cause harm to it, but it is best not to do deliberately. Usually, the standard of membrane is to be sassed with rubber for dozens of times without being damaged.


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