The raw materials for producing optical glass are oxides, hydroxides, nitrates and carbonates. Phosphates or fluorides are introduced according to the requirements of formulation. In order to ensure the transparency of glass, the content of coloring impurities such as iron, chromium, copper, manganese, cobalt and nickel must be strictly controlled. It is necessary to weigh accurately and mix evenly when mixing. The main production processes are smelting, forming, annealing and inspection.
There are single crucible batch melting method and continuous melting method in tank kiln (see kiln). The single crucible melting method can be divided into clay crucible melting method and platinum crucible melting method. Whatever melting method is adopted, agitator should be used to stir, and temperature and stirring should be strictly controlled to make the optical glass liquid highly uniform.
(2) The forming methods of optical glass include classical crucible breaking, rolling and pouring, but at present, leaking material forming (using single crucible or continuous melting to flow out liquid) is more and more widely used, which can directly draw rods or drop material pressing or leaking material to form large-sized blanks, so as to improve the utilization rate of material droplets and the yield of products.
(3) In order to eliminate the internal stress of glass and improve the optical uniformity, strict annealing system must be established and precise annealing must be carried out.
(4) The indexes of inspection and measurement are: optical constants, optical uniformity, stress birefringence, fringes, bubbles, etc.