1. Refractive index: When light propagates from vacuum to other media, the sine ratio of the incident angle and the refraction angle is called the refractive index of the medium. The higher the refractive index, the thinner the lens. For example, the refractive index of a single-focus double aspherical high-refractive lens is 1.665. This means that if you have a power of 500, the glasses made with this lens will be much thinner than a lens with a refractive index of 1.449. More beautiful! Therefore, in other words, the deeper the degree, the higher the refractive index required.

2. Abbe's number: Also known as dispersion coefficient, the larger the Abbe's number, the clearer you can see things. The smaller the value, the more serious the "rainbow" phenomenon of the lens will be, and the more detrimental it will be to the wearer. The Abbe number of a lens is generally between 30 and 60. The higher the refractive index of a lens, the lower the Abbe number. For resin lenses, the refractive index has a greater impact on the Abbe number. CR-39 lenses with a refractive index of 1.50 , its Abbe number is 58. The Abbe number of 1.56 refractive index is generally 36-38, while most domestic companies use acrylic materials for ultra-thin resin lenses with a refractive index of 1.6, and the highest Abbe number is only 32. The Abbe coefficient of the good high-definition anti-blue light series has reached 48! 

3. Anti-ultraviolet (UV): Ultraviolet rays are divided according to wavelength: near ultraviolet UV-A, ultraviolet rays with wavelengths of 320NM-400NM (nanometers), UV-B: ultraviolet rays with wavelengths of 280NM-320NM, and UV-C: ultraviolet rays of 200NM-280NM. . Damage to the eyes by ultraviolet rays: UV-A can easily cause corneal burns, vitreous opacity, and cataracts; UV-B: can easily cause keratitis, dry cornea, and red conjunctival congestion; UV-C: can easily cause eye fatigue.

4. Anti-radiation (EMI) and anti-static: Radiation is a kind of electromagnetic wave. The anti-radiation and anti-static functions of the lens are mainly to coat a layer of conductive material on the surface of the lens to guide the electromagnetic wave to the surroundings. For example, an anti-radiation lens has a good blocking effect on the radiation waves of current electronic products, while an anti-static lens helps prevent dust from being absorbed on the surface of the lens, making the lens cleaner.

5. Anti-blue light:

Anti-blue light is a coating designed to target the harmful blue light reflected by current smart devices. Anti-blue light series lenses have anti-blue light function, which can better protect the eyes from blue light.