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2022-11-10

About optical glass, you know?

Optical glass refers to glass that can change the direction of light propagation and can change the relative spectral distribution of ultraviolet, visible or infrared light. Optical glass can be used to manufacture lenses, prisms, mirrors and windows in optical instruments. Components made of optical glass are the key elements in optical instruments. An amorphous (glassy) optical medium material that transmits light. It can be used to make various optical components such as prisms, lenses, filters, etc. After the light passes through, it can change the propagation direction, phase and intensity. According to different requirements, optical glass can be divided into three categories: Colorless optical glass-in the visible and near-infrared quite wide band is almost completely transparent, is a very large amount of optical glass. According to the different refractive index and dispersion, there are hundreds of brands, which can be divided into two varieties, namely crown optical glass (represented by K) and flint optical glass (represented by F). Crown glass is borosilicate glass, which becomes flint glass when alumina is added. The main difference between the two is that the refractive index and dispersion of flint glass are very large, so spectral components are mostly manufactured with it. Radiation-resistant optical glass-has the properties of colorless optical glass, and can basically not change the performance under radioactive irradiation. Used for gamma-irradiated optical instruments, the same variety and brand as colorless optical glass. Its chemical composition is on the basis of colorless optical glass, adding a small amount of cerium dioxide to clean up the color center formed by high-energy radiation in the glass, so that the glass after irradiation, the light absorption change is very small. ③ Colored optical glass-has specific absorption or transmission properties for certain wavelengths of light. Also known as filter glass, there are more than a hundred varieties. Color filters can selectively absorb certain colors. Neutral filters absorb all wavelengths of light the same, but reduce the intensity of the beam without changing its color. The interference filter is based on the principle of light interference, the unwanted color is reflected rather than absorbed. The raw materials for the production of optical glass are some oxides, hydroxides, carbonates, and phosphates or fluorides are introduced according to the requirements of the formulation. In order to ensure the transparency of the glass, it is necessary to strictly control the content of coloring impurities, such as iron, chromium, copper, manganese, cobalt, nickel, etc. The ingredients require accurate weighing and uniform mixing. The main production processes are melting, forming, annealing and inspection. There are single crucible batch melting method and pool kiln (see kiln) continuous melting method. The single crucible melting method can be divided into clay crucible melting method and platinum crucible melting method. Regardless of the melting method, it is necessary to use a stirrer to stir, and strictly control the temperature and stirring to make the glass liquid highly uniform. Molding optical glass molding method has the classical broken crucible method, rolling method and pouring method, but at present more and more widely used leakage molding (with a single crucible or even melt out of the liquid), can directly pull the rod or drop pressure type or leakage molding large-size blank, improve the utilization rate of the drop and the yield of finished products. Annealing In order to clean up the internal stress of the glass to a great extent and improve the optical uniformity, a strict annealing system must be formulated and accurate annealing must be carried out. The indicators of the test are: optical constants, optical uniformity, stress birefringence, stripes, bubbles, etc.

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