The transmittance of the sunglasses

For light-colored sunglasses, the light transmission ratio should be >40%; For the sunshade mirror, the light transmission ratio ranges from 8% to 40%. The optical transmittance item is an important index to characterize the function of sunglasses. The current Chinese standard divides sunglasses into three categories according to this function: shading glasses, light sunglasses and special purpose sunglasses, while the European standard and international standard divide them into five categories.
Depending on the category, the purpose of sunglasses is very different. If the use of light-colored sunglasses for shading, the wearer will not be able to obtain a good effect of shading, such as a long time in the sun strong outdoor activities, the wearer will still be stimulated by stronger light and feel tired. Light-colored sunglasses generally play a decorative role, or used in the room where the sun is not strong. On the contrary, wearing a sunshade mirror indoors or in places that do not need to block strong sunlight will cause discomfort and fatigue due to excessive pupil dilation. In the sunshade mirror, the product with relatively small transmission is not suitable for the rider or driver to wear, because the rider or driver travels faster than the pedestrian, and the transmission ratio is too low will affect their reaction ability.