Important factors affecting the quality of optical glass
After the optical glass is smelted, it must be made into a certain size and shape of the blank, annealed, some varieties will be colored again, and tested as a finished product. Molding and color development is one of the important processes in the production process of colored optical glass. The molding method and the technical level of color development are one of the important factors that determine the yield and the best quality. One. The colored optical glass smelted in a crucible for glass molding adopts the casting method for molding. Pouring method can be divided into high viscosity pouring and thin viscosity pouring. Black transparent purple glass ZWB1 and ZWB3 are molded with dilute viscosity casting, and other varieties are molded with high viscosity. 2. Glass annealing. Optical parts made of colorless optical glass must have a high degree of optical uniformity and must be precisely annealed. The optical uniformity of colored optical glass requires no quotient of colorless optical glass. Its annealing requirement is mainly to eliminate the permanent stress generated in the forming, and slow annealing can be used. Annealing temperature, keeping time within the annealing temperature range, and cooling rate should be established through experimental methods according to different varieties and the size of glass wool damage. For colored optical glass with special optical uniformity requirements, precision invitations are also required. The coloring state of some colorants (such as Mrl, Se, etc.) will change during the annealing stage. For glasses containing such colorants, the annealing temperature should not only consider the stress relief, but also the change of the coloring state. 3. Color development of glass The so-called color development means that the glass after annealing inspection is reheated to a certain temperature (pregnancy temperature) and kept at this temperature for a certain period of time (color development time), so that the coloring compound in the glass appears to be certain The light latent characteristics. The glass that requires a color development includes yellow, orange, red, and near-infrared cut-off glass. The color temperature and the color time are determined through experiments. From the annealed bulk glass, take several small samples and heat them at different mixing degrees and different times. After cooling, grind, polish, set the spectral characteristics, and select the appropriate temperature and time. Different furnace numbers of glass, due to smelting. The thermal history during forming and annealing is not exactly the same, and the color temperature and time of each furnace number must be determined through experiments. The spectral characteristics of colored glass are greatly affected by the color temperature. In order to make the color of the large glass uniform, the color development should be carried out in a precision annealing furnace. The requirements of the precision annealing furnace are the same as those for the annealing of colorless optical glass. For near-infrared cut-off glass with a higher color rendering temperature, the glass is almost softened during color development. Asbestos paper should be used to separate the glass during the color development process. The quality inspection of colored glass such as stripes and bubbles should be carried out before the color development, because the color of the glass is dark after the color development, and it is difficult to inspect.