Application of Coating Technology in Lens and Limitations of Optical Lenses
The application of coating technology in optical lens processing-
The earliest lens is not coated, there is Even the internal extinction of the lens barrel and the blackening of the edge of the lens are not processed, and then a single-layer coating appears, but this is mainly used in military binoculars to realize the extinction of the lens and reduce the possibility of being discovered by the enemy (such as Zeiss top Daming’s T* coating was first developed for military use. In the field of civilian cameras, Kodak produced the first Ektra camera with a coated lens in 1941. However, the development of coating technology should start with Pentax’s introduction of the SMC-coated SMC lens in the early 1970s. Start counting.
The coating on modern optical lenses can be divided into two types. One is called antireflection coating, which increases the light transmittance, while the other coating is It changes the transmission characteristics of the color spectrum of an optical lens. For example, the optical material used in a lens in a lens has good refractive index and other indicators, but there is a yellowish phenomenon, so coat it with a spectrum Blocking film to correct the color cast back (the three princesses of Pentax use high-refractive glass, so they are slightly yellowish), and the development of coating technology can compensate for the shortcomings of some relatively inexpensive optical materials. The design of the lens It is no longer necessary to use expensive special formula optical glass as in the past, so new lenses generally have multiple coatings on the air contact surface of each lens. This also highlights the effect of coating on the lens. Important role.
Pentax launched the SMC super multi-layer coated lens in 1971, which can be regarded as the world at that time. Attention, although Nikon, Canon and Leica have mastered the multi-layer coating technology (3-4 layers) before this, the coating of more than 6 layers is still a difficult goal to accomplish.
On the other hand, Fuji claims that their electron beam coating EBC (E optical lens electron-Beam Coating) can reach 11 layers, which is already in the leading position. They will use EBC coating technology It was used in some movie camera lenses and used in the 1964 Olympic Games, but it was not used in the development of civilian lenses. After that, under the pressure of Pentax SMC, it gradually developed EBC and Super EBC Fujinon photographic lenses, and achieved good results. Market reaction.
multilayer coating makes it possible to develop modern ultra-wide-angle lenses and large zoom optical lenses. With the popularity of zoom lenses, the length of the focal length and the zoom range are gradually expanded (more optical components are required). In order to ensure the optical quality, multilayer coating technology becomes very important.
The interesting thing is that in fact almost all major optical lens manufacturers (including Canon, Nikon and Zeiss) pay a license fee for the guest to use some or all of the multilayer coating The process is to coat the surface of the optical element with a thin anti-reflection compound at a cost acceptable to the focusing lens. Leica still insists on his noble status, claiming that the multi-layer coating technology is very weak in controlling glare, and reducing the number of optical components to control glare is more effective.
The thickness of the lens is mainly determined by the degree. Nowadays, most spectacle lenses are made of resin, but I don’t know it. There are many kinds of resin, and many say it is. Imported from South Korea, in fact, the domestic lenses are still better than imported from South Korea to a certain extent.
You can find optical lenses of different grades and prices to compare. To talk about the thickness, it’s hard to tell the truth, because the lens is thinner behind the edge, and if it is 2000 degrees, the edge is about 4 millimeters thick.
Ultra-thin lenses have both optical glass lenses and resin lenses. Ultra-thin myopia lenses are suitable for people with high prescriptions.
Glass materials increase the refractive index by adding lead-containing heavy metal oxides to increase the density of the aspheric mirror and the material, and the refractive index is positively correlated with the specific gravity. The refractive index increases and the weight of the lens increases significantly. However, under the same power, the refractive index of glass lenses is higher than that of resin lenses.
Resin materials increase the refractive index by changing the molecular structure of the material. As the refractive index increases, the lens The weight does not necessarily increase, some may even decrease.
Ultra-thin lenses currently refer to lenses made of high-refractive index materials, which have the advantages of being lighter, thinner and more comfortable. Especially for patients with high myopia, because the diopter is too high, it appears that the lens has too many turns and the periphery is too thick. Just like the bottom of the bottle, the appearance is very unsightly. Therefore, you must choose a small frame when you wear glasses. It's small. The smaller the lens, the lighter the weight of the glasses, which can reduce the pain of oppressing the nose.