Optical lenses have been popular in China since 1996. After nearly 10 years of market promotion, they have occupied more than 85% of the market share, and more and more people have begun to use them. A safe, lightweight lens. However, in our actual work, we found that many friends have very little knowledge of resin films. After purchasing the lenses, they do not know the brand, refractive index, film type, use skills and life of the lenses.

　　一. Brand

　　 What is a brand is that it is widely recognized by everyone, in retail A product widely praised by the industry and customers in the market. The quality of this type of lens can reach Class A, and of course the price is the highest. A pair of 1.56 refractive index coated lens is at least 500 yuan. In European and American countries, it is a popular lens. In China, it is still a choice for a few people. Luxury. So what about domestic brand optical lenses? In fact, many of the above-mentioned brands are domestically produced, and many of the packaging is produced in China, so don't blindly believe in imported lenses.

　　 Many materials of domestic products rely on imports from Japan and South Korea. The internal testing standards of the company are divided into A, B, and C levels. A-level is generally used for export or OEM for first-line brands, and B-level is generally used by manufacturers to sell their brands directly to retail stores. The quality and price are very good. For example, 1.56 lenses, 100-200 products in the retail market. C-level will generally enter the wholesale market, supplying scattered customers and customers in remote areas, the price is cheap, many small retail stores in large cities, what package, what 3-4 discount 100 yuan frame and lens specials are basically this kind of products.

　　 Overview, first-line brands have high prices and naturally high quality grades. Brands in China Optical Lens can buy products above Grade B, which is also a cost-effective choice. Grade C lenses , Let's talk about it.

　　二、Refractive Index

　　 The material purchase parameter of the lens is based on the refractive index, which determines the price of the lens . The following is a list and brief description of the refractive index, we only talk about domestic brand lenses above the B level.

　　1.50 (1.499) The most common resin lens on the market, the refractive index is relatively low, and myopia can reach up to 600 degrees. If the frame is larger, the edge of the lens will be thicker. The price ranges from 50-200, which is suitable for elementary and middle school students. The power often changes and the lens needs to be changed. The price is relatively cheap.

　　1.56 (1.556) is currently a relatively popular resin lens with a medium refractive index, commonly known as super thin film, but now it should be called a medium refractive lens, which can reach 800 degrees of myopia conventionally. The price ranges from 10 focusing lens 0-500, and it is recommended for customers within 800 degrees to use.

　　1.61 (1.607) This can be called a super flake. The retail of domestic brands ranges from 300 to 600, and the thickness is compared with the previous two , A lot thinner. Recommended within 1000 degrees.

　　 The choice of glass material is very important, because different glass types have different characteristics.

　　 Designers generally use the refractive index and Abbe value of the glass as the degree of freedom of the design system. Reflectance refers to the ratio of the speed of light in vacuum to the speed of light in a specific material at a specific wavelength; the Abbe value of a material quantifies the amount of dispersion (change in dispersion rate) in a specific spectral range. For example, the higher the refractive index of the material, the stronger the ability to refract light, so the curvature of the lens needs to be smaller.

　　 In the case of an aspheric mirror with a higher refractive index, the spherical aberration value is smaller; and the speed of light passing through a material with a low refractive index is faster. A high Abbe number usually provides low dispersion and reduces chromatic aberration. In addition, some glass types have different transmission wavelength regions.

　　Glass density helps determine the weight of optical components and the diameter of the lens, which is more sensitive for weight-constrained applications. In addition, density generally refers to the ability to be used with glass, and has a certain ratio to the cost of materials. When dealing with applications that involve extreme temperatures and rapid temperature differences, the expansion coefficient of glass becomes its main proportion. Optomechanical designers must keep this in mind when designing optical components.

　　Many glass manufacturers provide products with different product names but the same material characteristics. Most manufacturers also modify their products and manufacturing processes to achieve their environmental goals (free of lead and arsenic).