How to process optical glass lens of microscope?

The processing of microscope optical glass lens is a complicated process, which mainly includes the following key steps:

Raw material preparation: choose high-purity glass material with excellent optical properties as the raw material of the lens. These glasses need to have specific optical properties such as refractive index and dispersion coefficient to meet the imaging requirements of microscope lenses. According to the size and shape of the required lens, the glass raw material is cut into rough blanks.

Rough grinding: Using grinding equipment, such as grinding machine, the surface of the blank is preliminarily ground to remove most of the surplus, so that the lens can reach the outline close to the final shape. In the process of rough grinding, abrasives such as silicon carbide are usually used, and the materials on the glass surface are gradually ground away through the rotation and pressure of the grinding disc. The shape of the lens can be changed quickly at this stage, but the surface roughness is relatively high.

Fine grinding: On the basis of coarse grinding, fine grinding is carried out to further improve the surface accuracy and smoothness of the lens. Finer abrasives, such as alumina or cerium oxide, will be used in fine grinding, and the rotating speed and pressure of the grinding disc will be controlled more accurately. Through fine grinding, the surface roughness of the lens can reach micron level or even higher precision, which makes preparations for subsequent polishing.

Polishing: Polishing is a key step in lens processing, aiming at obtaining extremely high surface smoothness and optical flatness. Put the lens on a polishing machine, and polish it with a polishing die and polishing solution. Polishing solution usually contains tiny particles such as cerium oxide. Through the relative movement between the mold and the lens surface, the micro-unevenness of the lens surface is gradually removed, so that the lens surface can reach nano-level smoothness, thus reducing the scattering and reflection of light and improving the light transmittance and imaging quality of the lens.

Centering grinding: determine the optical center of the lens and grind the edge of the lens to achieve the specified diameter and edge accuracy. This step is very important to ensure the accuracy of lens installation in microscope and the consistency of optical performance. Through high-precision centering edging equipment, the central deviation of the lens can be controlled in a very small range.

Coating: In order to improve the optical performance of the lens, such as increasing light transmittance, reducing reflection and preventing glare, it is necessary to coat one or more optical films on the lens surface. The methods of coating are usually physical vapor deposition (PVD) or chemical vapor deposition (CVD). By controlling the coating material, thickness and number of layers, different optical functions can be realized. For example, the antireflection film can make the transmittance of the lens reach more than 99% in a specific wavelength range, which greatly improves the imaging brightness and contrast of the microscope.

Quality inspection: Use all kinds of sophisticated inspection equipment to conduct comprehensive quality inspection of lenses. The inspection items include the radius of curvature, thickness, center deviation, surface roughness, optical uniformity and transmittance of the lens. For example, the surface flatness and optical defects of the lens can be detected by interferometer, and the transmittance of the lens at different wavelengths can be measured by spectrometer. Only after strict inspection, the lenses that meet the quality standards can enter the subsequent microscope assembly.