What is the transmittance of sunglasses lenses

I don’t know if you have paid attention to the packaging when you buy sunglasses. The transmittance is usually written on it. There are 1, 2, 3, and 4. What does this parameter mean? Ray-Ban RB4242 Male and female universal glasses frame 6201/13 Brown Transmittance Introduction Transmittance, also known as transmission coefficient, is the ratio of the luminous flux or auxiliary flux through the material or medium to the incident flux. The transmittance of a material depends on factors such as the direction of incident light, the molecular structure of the material, and the thickness of the material. The specific classification of transmittance is also divided into four categories according to the degree of light transmission of the lens, which can be called 'transmittance classification'. 1. 43%~80%. 2. 18%~43%. 3. 8%~18%. 4. 3%~8%. According to the requirements, the transmittance of driving mirrors should be greater than 8%, so category 4 sunglasses cannot be worn for driving. For UV protection, the first three types of uva allow 5% to pass through, and the fourth type of uva allows 0.5% to pass through. uvb are allowed to pass through 1%. There is also a classification, which can be called the 'sunglasses category1. Light-colored sunglasses, more than 40% light transmission. 2. Sun-shading mirror, light transmission 8%~40%. 3. Special purpose sunglasses (skiing, mountain climbing, beach, etc.), 3%~8%. Among them, light-colored sunglasses and sun-shading mirrors are required to identify traffic lights, and the three colors must be higher than 8%. Ray-Ban RB8056 Men’s Sunglasses 175/6Q Tortoiseshell Knowledge Expansion: What is UV-resistant polarized sunglasses? Polarized sunglasses with UV-resistant function are generally indicated in the following ways: a) Mark 'UV400': This means that the polarized sunglasses lenses are UV resistant The cut-off wavelength is 400nm, that is, the maximum value τmax(λ) of the spectral transmittance at a wavelength (λ) below 400nm is not more than 2%; b) Mark 'UV' and 'UV protection': This means that the polarized sunglasses lens is against ultraviolet The cut-off wavelength is 380nm, that is, the maximum value τmax(λ) of the spectral transmittance at a wavelength (λ) below 380nm is not more than 2%; c) Mark '100% UV absorption': This means that the polarized sunglasses lens has the effect of ultraviolet rays. The function of 100% absorption, that is, its average transmittance in the ultraviolet range is not more than 0.5%. The polarized sunglasses that meet the above requirements are the polarized sunglasses with protection against ultraviolet rays in the true sense. Related reading: sunglasses with degree du0026g sunglasses
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