Detection index of sunglasses: light transmittance

u003cbru003eThe light transmittance item is an important indicator to characterize the function of sunglasses. The light transmittance refers to the ratio of the transmitted light flux to the incident light flux. This ratio represents the amount of light transmitted by a lens (medium) in the visible light wavelength range. Overrate can also be understood as the amount of illuminating light (such as sunlight) that passes through the lens, which reflects the sun-shading effect of the lens. my country’s current product standards are divided into three categories according to this function: sun-shading mirrors, light-colored sunglasses and special-purpose sunglasses, and GB10810. 3 transmittance specifications and measurement method standards subdivide them into four categories. QB2457-1999 'Sunglasses' standard stipulates: A. The light transmittance of light-colored sunglasses is u003e40%; B. The light transmittance of sun-shading sunglasses is 8% to 40%; C. The light transmittance of special purpose sunglasses is 3% to 8%. . It is not difficult to see that the color of sunglasses from category A to category C is from lighter to darker. It can also be said that the filter ability of the lens is sequentially strengthened. The light transmittance of different types of sunglasses must strictly meet the above requirements. Different types of sunglasses have different uses. 1. The transmittance requirements of sunglasses. 2. Refer to ISO14889 for the transmittance requirements of driving mirrors. The traffic signal identification (packaging mark) should meet the following requirements: (1) Light transmittance The light transmittance rv of the driving mirror shall not be less than 8%. Daily driving mirror: Under the condition of using the standard light source D65, the light transmittance rv at the design reference point (or geometric center) must be greater than or equal to 75%. (2) The spectral transmittance r(λ) at any wavelength in the (5000～650) nm band is not less than 0.2rv. (3) The relative visual attenuation factor Q for traffic signal identification: Red: ≥0.8; Yellow: ≥0.8; Green: ≥0.6; Blue: ≥0.4. (4) In addition to meeting the requirements of the national standards for sunglasses, special-function driving mirrors should also meet the technical indicators for special functions indicated by the manufacturer.

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