cheap ray bans sunglasses can wind proof, anti glare, but also has beautiful appearance, and can protect the eyes from UV damage. All of this is due to the metal powder filter device, they can be in the light of the “choice”. Tainted glasses can selectively absorb part of the band consists of sun light, because it is using the metal powder is very fine (iron, copper, nickel, etc.). In fact, when the light from the lens, the so-called “interference” based on the process, the light has been reduced.
That is to say, when certain wavelengths of light (here refers to the ultraviolet A, ultraviolet B, sometimes there are infrared) through the lens, in the inner side of the lens toward the eye direction, they will cancel each other out. Overlapping is not an accidental phenomenon, the formation of light: the crest of a wave with the wave trough near together, leading to offset each other.
The refractive index of destructive interference phenomenon depends on the lens (deviate degree that the light from the air passing through different substances), also depends on the thickness of the lens. Generally speaking, thickness of lens, and the refractive index of the lens according to the differences in chemical composition and different.
Polarized glasses provide another eye protection mechanism. The light is polarized light reflective road special. The difference of the reflected light and direct light from the sun or any artificial light source is the problem of order.
Generally speaking, the reflected light is a kind of order of the light. Polarized lenses is especially effective in blocking the light, because it plays a role in filtering. This kind of lens only polarized wave by towards a certain direction motion, like the light “comb”. For the road reflecting problems, using polarized glasses can reduce the transmission of light, because light is not the way it through parallel motion.
Under normal circumstances, it can make the lens to maintain perfect transparency. Under the irradiation of sunlight, the crystal of silver will be separated, in the free state of silver formed small aggregates in the inside of the lens. These small silver aggregates be zigzag irregular block, they can not only absorb the light and transmission light, dark, the result of lens. In the case of light and dark, and re formation of crystalline lens, will return to the bright state.