How to process the optical lens substrate?

The processing of optical lens substrate is a complex and delicate process, which mainly includes cutting, grinding, polishing, coating and testing. The following is a detailed introduction for you:

cut

Selection of cutting process: cutting is to cut the original optical materials into optical lens substrate blanks with specific sizes and shapes according to the design requirements. Common cutting processes include diamond cutting and laser cutting, and the appropriate cutting process should be selected according to the properties, hardness, thickness and cutting accuracy requirements of optical materials. For example, for optical glass materials with high hardness and large thickness, diamond cutting process is usually used. Diamond has extremely high hardness, which can effectively cut optical glass, and high cutting accuracy can be achieved by controlling cutting parameters, such as cutting speed, cutting pressure, particle size of diamond tool, etc. For some optical crystal materials with low hardness and thin thickness, such as calcium fluoride crystal, laser cutting technology is more suitable. Laser cutting has the advantages of non-contact processing, high cutting speed, high cutting accuracy and small heat affected zone, which can effectively avoid mechanical damage and thermal stress deformation to optical crystal materials during cutting, thus ensuring the optical performance and dimensional accuracy of the cut optical crystal materials.

Cutting accuracy control: In the cutting process, the control of cutting accuracy is very important. Cutting accuracy directly affects the difficulty and accuracy of subsequent grinding and polishing processes, as well as the dimensional accuracy and shape accuracy of the final optical lens substrate. In order to ensure the cutting accuracy, it needs to be controlled from many aspects. First, choose high-precision cutting equipment. High-precision cutting equipment is usually equipped with advanced numerical control system, high-precision transmission device and positioning device, which can realize accurate control of cutting process and high-precision positioning of cutting position. For example, in some high-end diamond cutting equipment, the numerical control system can accurately control the cutting speed, cutting pressure and other parameters, the transmission device adopts high-precision ball screw and linear guide rail, which can realize the high-precision linear motion of the cutting tool, and the positioning device adopts high-precision grating ruler or laser interferometer, which can monitor the position of the cutting tool in real time, thus realizing the accurate control of the cutting accuracy, and the cutting accuracy can reach within 0.05 mm. Secondly, optimize the cutting process parameters. The selection of cutting process parameters directly affects the cutting accuracy and cutting quality. For example, in the diamond cutting process, too fast cutting speed will lead to increased wear of cutting tools and decreased cutting accuracy, and may also lead to defects such as cracks and edge collapse on the cutting surface; However, if the cutting speed is too slow, the cutting efficiency will be low and the production cost will increase. Therefore, it is necessary to optimize the cutting process parameters according to the properties, hardness, thickness and cutting accuracy requirements of optical materials through experiments and simulations to ensure cutting accuracy and cutting quality. In addition, in the process of cutting, it is necessary to strictly control the cutting environment. Factors such as temperature, humidity and vibration of cutting environment will affect the cutting accuracy. For example, the change of temperature will cause the parts of cutting equipment to expand with heat and contract with cold, thus affecting the accuracy and stability of cutting equipment; The change of humidity will lead to the adsorption of water on the surface of optical materials, thus affecting the cutting quality; Vibration will cause the cutting tool to shake in the cutting process, which will affect the cutting accuracy and quality. Therefore, it is necessary to install air conditioners, dehumidifiers, shock absorbers and other equipment in the cutting workshop to strictly control the temperature, humidity, vibration and other factors of the cutting environment to ensure the cutting accuracy and quality.

pestle

Rough grinding: the main purpose of rough grinding is to quickly remove most of the machining allowance on the surface of the cut optical lens substrate blank, so that the size of the substrate is close to the design requirements, and lay the foundation for the subsequent semi-fine grinding and fine grinding processes. In the process of rough grinding, a grinding disc or belt with large particle size is usually used, and the grinding pressure and feed speed are correspondingly large. For example, for the rough grinding of optical glass substrates, a grinding disc with a particle size of 80-120 meshes can be selected. The grinding disc with this particle size has a large abrasive particle size and a cutting edge, which can quickly cut the materials on the substrate surface during the grinding process, thus effectively removing most of the machining allowance on the substrate surface. At the same time, in order to ensure the efficiency and effect of rough grinding, it is necessary to adjust the grinding pressure and feed speed reasonably according to the material, hardness and machining allowance of the substrate. Generally speaking, the grinding pressure can be controlled between 1 and 3 MPa, and the feed speed can be controlled between 10 and 30 mm/min. Under such grinding parameters, sufficient friction and cutting force can be ensured between the grinding disk and the substrate surface, so as to quickly remove the substrate surface materials and improve the rough grinding efficiency. However, in the rough grinding process, due to the large friction and cutting force between the grinding tool and the substrate surface, the substrate surface will produce higher temperature and larger surface roughness. Therefore, in the process of rough grinding, it is necessary to pay attention to proper cooling and lubrication of the substrate surface to reduce the temperature of the substrate surface and the increase of surface roughness, and at the same time, it can prolong the service life of grinding tools and improve the processing efficiency and quality. For example, the surface of the substrate can be cooled by spraying cooling liquid on the surface of the grinding disk. Commonly used cooling fluids include water-based cutting fluid and oil-based cutting fluid, which can be selected according to the substrate material, processing requirements and environmental conditions. At the same time, in order to improve the grinding effect and processing quality, a proper amount of lubricants, such as extreme pressure additives and oiliness agents, can be added to the cooling liquid. These lubricants can form a lubricating film on the surface of the substrate during grinding, reducing the friction and wear between the grinding tool and the surface of the substrate, thus improving the grinding efficiency and processing quality and prolonging the service life of the grinding tool.

Semi-fine grinding: After rough grinding, most of the machining allowance on the substrate surface has been removed, but the surface roughness and dimensional accuracy still need to be further improved. Therefore, in the semi-precision grinding stage, the main purpose is to further reduce the roughness of the substrate surface, improve the dimensional accuracy and create good conditions for the subsequent precision grinding process while removing the remaining small machining allowance. In the semi-fine grinding process, a grinding disc or belt with moderate particle size is usually used, and the grinding pressure and feed speed are relatively small. For example, for semi-fine grinding of optical glass substrates, a grinding disc with a particle size of 150-240 mesh can be selected. The grinding disc with this particle size has moderate abrasive particle size and sharp cutting edge, which can cut the materials on the substrate surface evenly and finely during grinding, thus effectively reducing the roughness of the substrate surface and improving the dimensional accuracy. At the same time, in order to ensure the effect of semi-fine grinding, it is necessary to adjust the grinding pressure and feed speed reasonably according to the material and hardness of the substrate and the machining allowance after rough grinding. Generally speaking, the grinding pressure can be controlled between 0.5 MPa and 1.5 MPa, and the feed speed can be controlled between 5 mm/min. Under such grinding parameters, proper friction and cutting force can be ensured between the grinding disc and the substrate surface, so as to realize uniform and fine cutting of the substrate surface material, effectively reduce the roughness of the substrate surface and improve the dimensional accuracy. In addition, in the semi-fine grinding process, it is also necessary to pay attention to proper cooling and lubrication of the substrate surface to reduce the temperature of the substrate surface and the increase of surface roughness, and at the same time, it can prolong the service life of grinding tools and improve the processing efficiency and quality. For example, the surface of the substrate can be cooled by spraying cooling liquid on the surface of the grinding disk, and an appropriate amount of lubricant can be added to the cooling liquid to improve the grinding effect and processing quality.