Inspection Standard For Surface Cleanliness Of Optical Glass

Jan. 18, 2019

Optical Spherical Lens can change the direction of light propagation and can change the relative spectral distribution of ultraviolet, visible or infrared light. Components made of optical glass are key Customized Optical Components in optical instruments. The degree of cleanliness has a large impact on the quality of the product treated on the surface of the optical glass. Therefore, the cleaning treatment before the surface treatment is very important for the subsequent glass surface treatment process.

The following is a brief explanation of the inspection criteria for the surface cleanliness of optical glass.

(1) Contact angle method of glass surface and liquid

Water and ethanol are poured onto the clean glass surface to expand and completely wet, with a contact angle almost equal to zero. If the surface of the glass is contaminated, water and alcohol will not completely wet, showing a distinct and large contact angle.

(2) Air test method

Use a clean, moist air to blow the glass surface, placed in front of a black background, such as glass is clean, it will appear black, thin, uniform moisture film, called black trace. If the surface of the glass is polluted, the water vapor will condense into uneven water droplets, which are called gray marks.

(3) Static friction coefficient method on glass surface

Measuring the static coefficient of friction between solids and glass is a sensitive method for checking the cleanliness of glass surfaces. The cleaning surface has a high coefficient of friction, close to one. If the surface of the glass is stuck with grease or has an adsorption film, the static friction coefficient is reduced. For example, when the glass adsorbs the stearic acid layer, the static friction coefficient is only 0 or 3.

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