Glass lenses have more scratch resistance than lenses of other materials, but their relative weight is also heavy, and their refractive index is relatively high: 1.523 for ordinary sheets, 1.72 or more for ultra-thin sheets, and up to 2.0.
The main raw material for glass lenses is optical glass. The refractive index is higher than that of the resin lens, so the glass lens is thinner than the resin lens in the same degree. The glass lens has good light transmittance and mechanochemical properties, and has a constant refractive index and stable physical and chemical properties. The lens with no color is called optical white (white), and the pink for colored film is called Crocker lens (red). Crockex lenses absorb UV light and absorb light slightly. The glass sheet is superior in optical properties, is not easy to scratch, and has a high refractive index. The higher the refractive index, the thinner the lens. However, the glass piece is fragile and the material is heavy.