What are smart glasses
What's a good material for glasses
1、 Natural material crystal lens
The main component of this material is silica, which is usually divided into colorless and tawny. The material is not easy to wear and has low coefficient of thermal expansion. Because of its unique transparency to ultraviolet, it is easy to cause visual fatigue when wearing. In addition, due to the uneven density of the crystal material, the lens often contains impurities, so it is easy to produce birefringence in use.
2、 Glass lens
It is the main material for lens production, which can be divided into the following five types:
This kind of lens is also called white plate, white plate and optical white plate. Its basic composition is sodium titanium silicate. It is colorless, transparent and has high definition. It can absorb ultraviolet light below 330a. Adding CeO2 and TiO2 to baituopian can prevent the UV below 346a, so it is also called UV white pian. The visible light transmittance is 91-92%, and the refractive index is 1.523.
Commonly known as kexipian, the transmittance is 87%. This kind of lens has two-color effect. It is light blue in sunlight (so it is also called blue sheet) and light red in incandescent lamp (because it contains metal element neodymium). It can absorb ultraviolet light below 340a, part of infrared light and yellow visible light below 580A.
CeO2 and MnO2 are added to the Baituo lens material to improve the ultraviolet absorption capacity. This kind of lens is light red under sunlight and incandescent lamp, so it is also called red sheet. It can absorb ultraviolet light below 350A, and its transmittance is more than 88%.
The refractive index of this kind of lens is increased to 1.70 by adding TiO2 and PbO to the raw material. Its surface reflectance is high, about 1 / 3 thinner than ordinary white or red film of one diopter. It is suitable for high myopia and has beautiful appearance. In addition, due to the low Abbe coefficient and large chromatic aberration, the ultra-thin film is easy to cause the decrease of peripheral vision, and the color will appear when the line is bent.
1.60 glass lens
The refractive index of this kind of lens is 1.60, which is thinner than that of ordinary glass lens (1.523) and smaller than that of ultra-thin lens (1.70), so it is very light. It is very suitable for medium power wearers. Some manufacturers call it ultra light ultra-thin lens.
3、 Plastic lens
The refractive index is 1.499 and the specific gravity is 1.19. The surface is easy to scratch due to the poor hardness of the material. It used to be used for hard contact lenses, but now it is used for current lenses, such as presbyopic lenses. It is lighter than glass lens, but its surface hardness and optical properties are not as good as glass lens
The most representative is CR-39, which is made of hard and transparent material with refractive index of 1.499 and transmittance of 92%. From the material characteristics, it has good thermal stability, no deformation below 150 ℃, water resistance, corrosion resistance (except strong acid) is also good, insoluble in general
1. The specific gravity is 1.32, which is half of that of glass
2. Impact resistant, non fragile, strong sense of security (in line with FDA standards);
3. Comfortable to wear:
4. It is easy to process and widely used (including half frame and frameless frame);