It can also be read from the screen that the light transmittance of the glasses is 95.4% and the blue light transmission rate is 76.7%. The UV cut-off wavelength is 393nm, which means that the lens can block more than 98% of ultraviolet rays below the 393nm wavelength. As shown in the figure below, the purple light transmission is 2.4% (UV rejection rate is 97.6). The UV cut-off wavelength is calculated by measuring the ultraviolet transmittance of this wavelength. The instrument has a built-in ultraviolet light source of a certain wavelength. Use transmission meter to measure UV cut-off wavelength. It can’t measure the anti-ultraviolet performance of the lens.Ģ. If the banknote's anti-counterfeit mark is not visible after turning on the flashlight, it means that the lens has a blocking effect on the ultraviolet light emitted by the flashlight However, this method can only make a simple qualitative judgment on whether the lens has anti-ultraviolet effect. Place the banknote with the anti-counterfeit mark under the ultraviolet currency detector flashlight and put the lens under test in the middle. EU widely used standard is that ultraviolet light below 380nm wavelength can be blocked by 95%.ġ. Some countries also define UV400 as the ultraviolet light below 400nm wavelength can be blocked from 99% to 100%. 100% UV absorptionġ00% UV absorption means that the lens has the function of 100% absorption of ultraviolet rays, that is, the average transmittance of the entire ultraviolet band is less than 0.5%. UV380 means that the UV cut-off wavelength of the lens is 380nm, which means that the maximum transmittance of ultraviolet rays that below 380nm is less than 2% (98% or more is cut off). UV 400 means that the UV cut-off wavelength of the lens is 400nm, which means that the maximum transmittance of ultraviolet rays that below 400nm is less than 2% (above 98% is cut off).
The following are several standards for lenses: 1. From the relationship E hc /, we see that longer wavelength visible light (400 to 800 nm) is less energetic (70 to 40 kcal/mole) than light in the accessible shorter wavelength (200 to 400 nm) near ultraviolet region (150 to 70 kcal/mole).
The spectacle lens logos divided by UV value mainly include UV380, UV400, 100% UV absorption, UV anti-ultraviolet, etc. Absorption of visible and/or ultraviolet light by a molecule introduces energy sufficient to break or reorganize most covalent bonds.