Commonly used optical filter cleaning methods are:
Commonly used solvents are aqueous solutions (acid or alkali solutions, detergent aqueous solutions, etc.); anhydrous solvents (ethanol, acetone, emulsions, etc.). The type of solvent is usually selected according to the nature of the contamination on the surface of the optical filter.
1. Scrub and dip
The easiest way to scrub is to wipe the surface of the optical filter with absorbent cotton, lens tissue, a rubber roller or a brush dipped in water, alcohol, scouring powder, chalk, etc. When scrubbing, it is necessary to prevent the optical filter from being scratched, and at the same time, the residual cleaning powder and chalk on the surface should be washed with pure water and ethanol.
Another common method is to place the optical filter in a container of solvent for immersion cleaning. After soaking for a certain period of time, use tweezers or other special fixtures to take out the cleaned optical filter and dry it with pure cotton cloth. This method requires simple equipment, convenient operation and low cost.
2. Jet cleaning
In order to improve the cleaning efficiency, the spray cleaning method is commonly used in production. The moving fluid is applied to the contaminants on the glass surface, and the shear force is used to destroy the adhesion between the contaminants and the surface of the optical filter, and the contaminants are separated from the optical filter. The surface is then carried away by the fluid.
Heat treatment is a relatively simple surface cleaning method, which can remove the organic dirt adhering to the surface of the optical filter and the adsorbed moisture, such as heating under vacuum, the effect is better. Generally, the temperature of optical filter heating and cleaning treatment is 100~400℃, and it can be heated to 450℃ under ultra-vacuum to obtain atomically clean surface.
The surface of the optical filter is treated with organic solvent vapor, and the grease film on the surface of the optical filter can be removed within 15s to 15min, which can be used as the last cleaning process. Commonly used organic compounds are ethanol, isopropanol, trichloroethylene, carbon tetrachloride, etc.
Ultrasonic cleaning is to place the optical filter in a stainless steel container with cleaning liquid, and the bottom or side wall of the container is equipped with a transducer to replace the input electrical oscillation with mechanical oscillation. (1MHz) ultrasonic vibration for cleaning.