Optical filter is made of plastic or glass and special dye. The transmissivity of glass sheet is similar to that of air. All colored light can pass through, so it is transparent. However, after dye, the molecular structure changes, and the refractive index also changes, and the passage of some colored light changes. For example, a white light passing through a blue filter emits a blue light, while the green light and red light are very few, most of which are absorbed by the filter.
Color filter is used to attenuate (absorb) some light bands in the light wave or precisely select the small band light wave to pass through, and reflect (or absorb) other bands that do not want to pass through. 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 the light wave.
All optical elements are precision instruments, especially optical filters, and the surface is easily scratched. Improper cleaning and storage may damage the surface of the filter surface, reduce its application performance and shorten its service life. Therefore, the correct way of maintenance is very important. Let's take a look at the small details of optical filters in normal use:
1. In the normal use process, the filter should be taken and placed as carefully as possible. At the same time, pay attention to the external environment to prevent the zipper and button of the clothes from scratching the filter, or put the filter in a dirty or dusty environment.
2. When contacting the filter, it is necessary to wear fingertips to avoid the salt and acid substances on the hands from corroding the substrate surface.
3. Take the edge of the filter by hand when taking the filter, and do not touch the light transmitting surface of the filter even with a finger sleeve.
4. Filters should be placed on soft, clean objects, not on glass, metal, tables, or dirty paper.
5. When storing, it should be wrapped in clean capacitor paper or special lens cleaning paper. The best storage temperature is about 23 ℃, and the humidity is not higher than 40%. Better in a dry storage cabinet.
6. Do not stack the filters together to avoid wear.
7. If there are stains or finger marks on the surface, it can be wiped with anhydrous ethanol or similar functional solvent. The specific method is as follows: put on the dust-free fingertip, soak the towel with anhydrous ethanol, drag the edge of the towel soaked with ethanol, and move in a single direction on the filter surface. Wipe as lightly as possible.