What should be paid attention to in polishing quartz optical glass?

The polishing process of quartz optical glass needs to pay attention to the selection of polishing materials, equipment debugging, process parameter control, etc., in order to ensure high-quality polishing effect. The specific precautions are as follows:

Selection of polishing materials

Polishing powder: Appropriate polishing powder should be selected according to the characteristics and polishing requirements of quartz optical glass. Cerium oxide polishing powder is a common choice, which has high polishing efficiency and good polishing quality, and can effectively remove scratches and damaged layers on the glass surface. For the polishing of high-precision optical components, it is necessary to select polishing powder with uniform particle size and high purity to ensure the surface smoothness and optical performance after polishing.

Polishing pad: the performance of polishing pad has an important influence on polishing effect. Common polishing pads include polyurethane polishing pads and wool polishing pads. Polyurethane polishing pad has good elasticity and wear resistance, can provide uniform polishing pressure, and is suitable for rough polishing and semi-fine polishing; Wool polishing pad is soft in texture and can obtain high surface finish, which is often used for fine polishing. When selecting the polishing pad, we should comprehensively consider the polishing process and the shape and size of the glass.

Debugging of polishing equipment

Rotational speed and pressure: The rotational speed and applied pressure of polishing equipment need to be adjusted according to the thickness, hardness and polishing stage of quartz optical glass. In the rough polishing stage, the rotating speed and pressure can be appropriately increased to speed up the removal of materials on the glass surface, but attention should be paid to avoid glass breakage or new scratches caused by excessive pressure. After entering the fine polishing stage, the speed and pressure should be reduced to obtain a smooth surface. Generally speaking, the speed of rough throwing can be between 100 and 300 revolutions per minute and the pressure is between 0.1 and 0.5 MPa; During fine polishing, the rotating speed can be reduced to 50-150 rpm, and the pressure is 0.05-0.2MPa.

Motion trajectory: Ensure that the motion trajectory of the polishing head is uniform and covers the whole glass surface, so as to avoid uneven local polishing. For quartz optical glass with complex shape, it may be necessary to control the movement of polishing head by special fixture or programming to ensure the consistency of polishing quality.

Control of polishing process parameters

Concentration and flow rate of polishing solution: The concentration and flow rate of polishing solution have a direct impact on the polishing effect. Too high concentration may lead to too fast polishing speed, but it is easy to leave residues on the glass surface; If the concentration is too low, the polishing efficiency is low. Generally speaking, the concentration of cerium oxide polishing solution is between 5% and 15%, and the specific concentration can be adjusted according to the actual polishing situation. At the same time, it is necessary to control the flow rate of polishing solution to ensure that the glass surface is always covered with an appropriate amount of polishing solution during polishing, usually the flow rate is between 50-200 ml per minute.

Polishing time: Polishing time needs to be determined according to the initial surface quality of glass, polishing requirements and the performance of polishing equipment. Too long polishing time may lead to excessive polishing of glass surface, surface deformation or optical performance degradation; If the polishing time is too short, the expected polishing effect cannot be achieved. In practical operation, it is necessary to determine the appropriate polishing time through experiments and experience, which generally ranges from several minutes to dozens of minutes.

Control of environmental conditions

Temperature and humidity: The ambient temperature and humidity during polishing have certain influence on the polishing quality. Too high temperature may lead to too fast evaporation of polishing solution, which will affect the polishing effect; Too high humidity will easily cause water vapor condensation on the glass surface, which will affect the performance of polishing powder. Generally speaking, the temperature of the polishing workshop should be controlled at 20℃-25℃ and the humidity should be controlled at 40%-60%.

Cleanliness: It is very important to keep the polishing environment clean. Dust and impurities in the air may fall on the glass surface, causing new scratches or affecting the polishing effect. Therefore, the polishing workshop should be well ventilated and cleaned regularly, and air purification equipment can be used when necessary to ensure the cleanliness of the polishing environment.

Quality inspection and control

Surface quality inspection: During the polishing process, it is necessary to regularly inspect the surface quality of quartz optical glass. Optical microscope or electron microscope can be used to observe the defects such as scratches and pits on the glass surface, and surface roughness can be measured by surface roughness measuring instrument. Once it is found that the surface quality does not meet the requirements, the polishing process parameters should be adjusted or the polishing materials should be replaced in time.

Optical performance testing: For optical quartz glass, the optical performance testing after polishing is particularly important. Optical parameters such as light transmittance, refractive index uniformity and surface shape accuracy of glass are detected by spectrophotometer, interferometer and other instruments to ensure that the polished glass meets the requirements of optical system.

In addition, operators need to wear clean gloves and masks during polishing to avoid skin grease and dust from polluting the glass surface. At the same time, we should operate in strict accordance with the operating procedures to ensure our own safety and the normal operation of the equipment.