Introduction

The main raw material of glass lens is optical glass. The transmittance and mechanical and chemical properties of glass lens are relatively good, with constant refractive index and stable physical and chemical properties.

Progressive lenses are developed on the basis of bifocal lenses. The use rate in Europe and the United States is relatively high, and the time of matching in China has only begun in nearly 10 years. Progressive lens refers to the gradual transition between the two focal lengths by using polishing technology in the transition between the upper and lower focal lengths, which is called progressive lens. It can be said that progressive lens is a multi-focal lens. When the wearer observes the far/near objects, in addition to not having to remove the glasses, the movement of vision between the upper and lower focal lengths is also gradual. There is no sense of fatigue that the eye must constantly adjust the focal length when using the dual-focus type, and there is no obvious dividing line between the two focal lengths. The only disadvantage is that there are interference areas of different degrees on both sides of the progressive film, which will make the surrounding field of vision produce swimming sensation.