Optical Glass Production Process and Transmittance Detection
1. Production and processing methods of optical glass
The raw materials for producing optical glass are some oxides, hydroxides, nitrates and carbonates and phosphates or fluorides are introduced according to the requirements of the formula. In order to ensure the transparency of glass, the content of colored impurities must be strictly controlled, such as iron, chromium, copper, manganese, cobalt, nickel, etc. It requires accurate weighing and uniform mixing during batching. The main production processes are smelting, forming, annealing and inspection.
① Smelting: There are single crucible intermittent melting method and continuous kiln melting method (see kiln). Single crucible melting method can be divided into clay crucible melting method and platinum crucible melting method. No matter what kind of smelting method is used, it needs to be stirred with a stirrer. The temperature and stirring are strictly controlled to make the glass liquid highly uniform. Clay crucible can smelt most crown glass and flint glass, the cost is low. It is used when the melting temperature of the glass exceeds the use temperature of platinum. Platinum crucibles can smelt glass with high quality and serious erosion to clay crucibles, such as heavy crown, heavy barium flint, rare earth glass and fluorophosphorus glass. However, high-frequency heating can be used for the production of glass with a large tendency to crystallize, requiring rapid cooling and certain atmosphere requirements.
Since the 1960s, countries have successively used continuous kiln smelting lined with platinum, which has greatly increased the output and quality of optical glass. This is the main trend in the development of optical glass production processes.
②The molding methods of forming optical glass include classical crucible method, rolling method and pouring method, but currently, leakage molding is used more and more (using a single crucible or continuous melting out of the liquid), which can directly pull the rod.
③ Annealing. In order to eliminate the internal stress of the glass to a greater extent and improve the optical uniformity, it is necessary to formulate a strict annealing system and carry out precision annealing.
④ Indications measured by inspection are: optical constant, optical uniformity, stress birefringence, stripes, bubbles, etc.
2. Optical glass transmittance detection method
As mentioned above, the most indispensable step in the production and processing of optical glass is detection. The optical uniformity and transmittance of optical glass are important detection indicators for the quality of optical glass. We can use LS108H spectrum transmission meter to detect the specific light transmittance and optical uniformity of optical glass. LS108H spectrum transmission meter is a general-purpose light transmittance test instrument that can measure visible light 550nm, ultraviolet 365nm and infrared 940nm. The spectrum transmission meter adopts a parallel light path design and the test of thick material data is also accurate; The test aperture is 3mm and it is no problem to test materials with small size. Therefore, customers who have testing requirements for the three parameters of light transmittance, ultraviolet and infrared can choose this LS108H spectrum transmissio meter.
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