The reason why optical crystals can be precision molded is mainly due to the development of mold materials that do not adhere to softened optical crystals.
The original
high precision optical waveplate molding method is a press molding in which a molten crystal optical blank is poured into a low temperature mold which is higher than 50 ° C above the optical crystal conversion point. This method is not only prone to adhesion of optical crystals to the mold surface of the mold, but also the product is prone to pores and cold mold marks (wrinkles), and it is difficult to obtain ideal shape and surface accuracy. Later, using a special type of precision-molded die, in an oxidizing-free environment, the optical crystal and the mold are heated together to the vicinity of the softening point of the
high-quality laser grade optical waveplate, and the optical crystal and the mold are at substantially the same temperature. The mold presses the optical crystal. Next, while maintaining the applied pressure, while cooling the mold, the temperature is lowered below the conversion point of the optical crystal (the optical crystal viscosity at the softening point of the optical crystal is about 107. 6 poise, the conversion point of the optical crystal) The optical crystal viscosity at that time is about 1013. 4 poise). Such a method of performing isothermal pressing with an optical crystal together with a mold is called an isothermal pressing method, and is a method which is relatively easy to obtain high precision, that is, a mold surface which is easily and accurately copied. The disadvantage of the manufacturing method of such an
optical waveplate manufacturer optical component is that heating and heating, cooling and cooling all take a long time, so the production speed is very slow. In order to solve this problem, an effective improvement was made to this method, that is, several molds were used in one molding device to improve production efficiency. However, the cost of aspherical molds is high, and the use of multiple molds is bound to result in excessive costs. In response to this situation, further research has been conducted to develop a non-isothermal pressurization method which is similar to the original lens blank forming conditions, thereby improving the production speed of each mold and the service life of the mold. In addition, others are researching and developing a method of directly molding an optical crystal flowing out of a melting furnace.
