After the optical lens is finely ground by the abrasive solution, the surface of the lens still has about 2-3 m thick crack layer, the method to eliminate this crack layer is polishing. The polishing mechanism is the same as that of grinding, except that the tools materials are different from the polishing fluids. The polishing materials used include cloth, polished skin and pitch. Usually, high-precision polishing surface is achieved, and the most commonly used material is high-grade polishing asphalt. Use asphalt to polish, it is to borrow by asphalt meticulous surface, drive polishing liquid grinding lens surface heat, make glass melt flow, melt to rough vertex and fill crack bottom, gradually remove crack layer.

At present, the polishing powder used for polishing glass lenses is mainly cerium oxide (CeO2), and the proportion of polishing solution is different according to the different polishing periods of the lenses. Generally, a higher concentration of polishing solution is used when the initial polishing and polishing die meet the die, and a dilute concentration of polishing solution is used after the surface of the lenses is bright. In order to avoid the mirror produce orange peel phenomenon (lens surface atomization).

Polishing and grinding using the same motion mechanism, in addition to polishing tools and working liquid is not the same, polishing

The required environmental conditions are also more stringent than during grinding. General polishing should be noted as follows:

The surface of polishing asphalt and polishing liquid can not have impurities, otherwise it will cause mirror scratches.

Polishing asphalt surface should be consistent with the surface of the lens, otherwise the polishing will produce jumping, and thus bite the polishing powder and scratch the lens surface.

Before polishing, it is necessary to determine whether the surface of the lens is scratched or punctured after grinding. The size and material of the polishing tool are appropriate.

Whether the hardness and thickness of asphalt are appropriate.

In the process of polishing, attention must be paid to the condition of the lens surface and the accuracy check. For the inspection of lens surface defects, because the inspection process is judged by personal vision and method, the inspector should have a deep understanding of the specifications of scratches and sand holes, and should often compare the standard samples of scratches and sand holes to ensure the correctness of inspection.