一、 Natural material-crystal lens
The main component of this material is silica, usually divided into colorless and dark brown two kinds. Material is not easy to wear, thermal expansion coefficient little. Because it has unique transparency to ultraviolet ray, easily causes visual fatigue when wear. In addition, because crystal, this kind material density uneven, the lens often contains impurities, easy to produce the double refraction when using.
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二、 Glass lense
̥It is the main material of product lens, specific divided into the following five kinds of:
1 Toric lense (Toric)
This lens is also known as white prop films, white films, optical white film, the basic ingredients is the sodium titanium silicate, colorless, higher definition of transparent, and can absorb ultraviolet under 330A. Joined Ceo2, the Tio2 to white-prop film can prevents under UV 346A, is also known as UV white film. Visible through rate is 91-92%, refractive index is 1. 523.
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2, Crocus film
Commonly known as Fox films, light transmission rate of 87%. Such lenses has double color effect, pale blue (also known as blue-chip) in daylight and under incandescent light red (due to the presence of metals neodymium), can absorb UV under 340A, part of the infrared and 580A yellow visible light.
3, Ryan Crocker game piece
Commonly known as the the Clexane piece, add Ceo2 and Mno2 to white prop lens materials, can increase the capacity of absorb ultraviolet. Such lenses show light red in both daylight and incandescent, it is also known as red tablets. It can absorb ultraviolet below 350A, the light transmission rate is 88%.
4, ultra-thin films
Such lenses add Tio2, Pbo to the raw materials, so that the refractive index increased to 1. 70. Its high surface reflectivity, thinner 1/3 than white film or red piece of one diopter, suitable for high myopia to wear, looks beautiful. In addition due to low Abbe coefficient and large chromatic aberration, ultra-thin films is easy to cause peripheral vision reduced, there will has color when lines bend.
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5, The 1. 60 glass lens
This lens refractive index is 1. 60, thinner than ordinary glass lenses (1. 523), while (1. 70) smaller proportion of the ultra-thin lenses, so very light, very suitable for the middle degree wearer, some manufacturers call it ultra-light ultra-thin lens.