Optical filter is an optical device used to select the required radiation band. One common feature of filters is that no filter can make the image of the celestial body brighter, because all filters absorb certain wavelengths, making the object darker. The filter is made of plastic or glass and special dyes. Red filters can only let red light pass through, and so on. The transmittance of glass plate is similar to air, all colored light can pass through, so it is transparent. However, after dye is dyed, the molecular structure changes, refractive index changes, and the passage of some color light changes.
Filters are widely used in photography. Color filter is an optical filter that expresses color. It can select the small range of light wave to pass through accurately, and reflect off other unwanted bands. Color optical filters are usually installed in front of the light source, so that people can receive saturated light of a certain color. 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 maintenance method is very important.
Here we will discuss the small details of optical glass filters in the ordinary use process:
1. In the ordinary use process, we should take and place it as carefully as possible, and pay attention to the external environment to prevent scratch the filter.
2. When contacting filter, finger sleeve should be taken to avoid salt and acid on hand from corroding the surface of substrate.
3. When taking the filter, you should hold the edge of the filter by hand. Even if you have a finger sleeve, you should not touch the light transmission surface of the filter.
4. Filters shall be placed on soft and clean objects, not on glass, metal, table, or unclean paper.
5. When storing, it should be placed in clean capacitor paper or special lens cleaning paper. The storage temperature is better than 23 ℃, and the humidity is not higher than 40%. It's better to put it in a dry storage cabinet.
6. Clean the surface immediately when it is found to be stained. Because dust can easily scratch the surface.
7. If the acid left by fingers is too long, it is easy to react with the coating material, which will become permanent stain. Therefore, the surface of filter should be cleaned in time.
8. If there is stain or finger print on the surface, wipe with anhydrous ethanol or similar functional solvent. The specific methods are as follows: put on the dust-free finger sleeve, wet the towel with anhydrous alcohol, drag the edge of the towel soaked with ethanol, and move in a single direction on the filter surface. During the wipe process, try to use as much force as possible, too much pressure may damage the filter surface. The purpose of using solvents is to dissolve the adhesive in the surface residue of the filter. But it is worth noting that any cleaning can reduce the surface level at a micro level.
9. Do not stack the filters together to avoid wear.