How to judge the optical filter products as good?
To judge whether the filter is a good product, we start from the following aspects.
1. When the quality index of the filter requires that the scratch grade is or better than this grade, there shall be no dense scratches on the surface of the filter, that is, four or more ≥ 10 # scratches are not allowed in any area of the filter.
2. When the scratch number of the filter does not exceed the number required by the surface quality, and there is no large scratch on the filter, the sum of all products of the scratch number multiplied by the ratio of the scratch length to the filter diameter shall not exceed the large scratch number.
3. The number of scratches of the filter does not exceed the number required by the surface quality, but when there are large scratches on the filter, the sum of the lengths of even large scratches should not exceed the number of direct scratches on the filter.
4 when there is a large scratch on the filter product, and the large scratch does not exceed 1 / 4D, the sum of the product of all stages of scratches multiplied by the ratio of scratch length to filter diameter shall not exceed half of the number of large scratches.
5. When the scratch level of the filter exceeds the scratch level required by the surface, the filter is not qualified.
Optical filter as far as optical lens is concerned, the filter on it is usually coated, through a special film to let part of the light pass through or hinder part of the light pass through. Now there is a kind of bimodal filter, that is, dual channel coating. Two films are coated on one lens to achieve the effect of two kinds of filters, such as ir650 + 950, It allows 650nm visible light to enter during the day and 950nm infrared light to enter at night, but the two do not affect each other.
The optical sheet is made by adding special dye into the plastic or glass substrate or evaporating optical film on its surface, which is used to attenuate (absorb) some light bands in the light wave, or to accurately select a small range of light waves to pass through, while reflecting (or absorbing) other unwanted bands. By changing the structure of the filter and the optical parameters of the film, various spectral characteristics can be obtained, so that the filter can control, adjust and change the transmission, reflection, polarization or phase state of light wave. The classification method of filters is generally classified according to spectral band, spectral characteristics, film material, application characteristics and other characteristics