Lens, lens, also known as the mirror heart, is the drawing heart after the tray, suitable for the clip placed in the frame, so called the mirror heart. Its form is horizontal and vertical, and it is an easy and convenient installation.
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. A lens without color is called an optical white (white film), and a pink film in a colored film is called a Crocks lens (red film). Crockex lenses absorb UV light and absorb light slightly.