Wear glasses at ordinary times, digital cameras, all kinds of household appliances, and even money on anti-counterfeiting technology, with optical thin film inseparable relationship, the generation of optical thin film is an important symbol of modern technology development, it is contemporary photoelectric technology support, communications and other accessories.
In the kinds of optical thin film, reflective film is a kind of typical optical thin film.
Reflective film in general can be divided into two kinds, one kind is metal reflective film, one kind is the dielectric reflective film.
In addition, there is the combination of these two metal dielectric reflective film, function is to increase the reflectivity of optical surface.
General metal have larger extinction coefficient.
When the beam from the incoming air to metal surface, light amplitude attenuation rapidly into the metal, cut into the metal inside the light corresponding to, and reflected light can increase.
The extinction coefficient, the greater the amplitude attenuation of light more quickly, the less light energy into the metal inside, the higher the reflectivity.
People always choose the extinction coefficient is larger, the optical properties of a relatively stable metal as the metal film material.
Commonly used in ultraviolet band of thin metal materials is aluminium, the visible light region commonly used aluminum and silver, gold, silver and copper is commonly used in the infrared region, in addition, chromium and platinum also often make some special film coating materials.
Because the materials such as aluminum, silver and copper in easily oxidized in the air and reduce the performance, so must be preserved electricity dielectric film.
Commonly used coating materials have a silicon oxide, magnesium fluoride, silica, 3 oxidation 2 aluminium, etc.
Metal reflective film preparation technology of the method is simple, working wavelength range is wide;
The disadvantage is that light loss is big, could not have a high albedo.
In order to further improve the reflective metal reflective film, you can add several layers of plating must be outside of the membrane thickness of the dielectric layer, composed of metal dielectric reflective film.
It should be pointed out that, metal dielectric film increased a certain wavelength (
Or a wave area)
The reflectivity, destroyed the characteristics of the metal film neutral reflection.
The dielectric reflective film is established on the basis of multiple beam interference.
In contrast to the coating, on the optical surface coated with a layer of film refractive index is higher than the base material, can increase the reflectivity of optical surface.
The simplest multilayer reflection is high and low refractive index by alternate deposition of two kinds of material, the optical thickness of each layer for a certain wavelength of a quarter.
Under these conditions, to participate in the reflected light vector on the surface of the superposition of all walks of life, the same direction of vibration.
Increase with the increase of the synthetic amplitude with the thin film layer.
Aluminum foil reflective film Dike aluminum foil insulation coil, also known as barrier membrane, heat insulation film, foil, thermal film, reflective film, etc.
By the aluminum foil cover + polyethylene film + fiber braid + metal coated with hot melt glue line pressure, aluminum foil coil heat insulation, waterproof, moisture-proof function.
Aluminum foil insulation coil of sunlight absorption (
Solar radiation absorption coefficient)
Very low (
, with excellent heat insulation performance, can reflex fell more than 93% of radiant heat, is widely used in building roof and exterior wall heat insulation.
Is a kind of corresponding antireflection film, the main effect is to improve the diffraction of light, can make people for a long time watching text and graphics.
This requires less smooth reflecting surface antireflection thin film.
Reflective film largely supported metal products such as far, reflective film packaging products, reduce the oxidation of the product, contribute to its long storage, increase its service life.