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How to determine the pros and cons of optical lenses in the production process of optical glass
The raw materials for the production of optical glass are some oxides, hydroxides, nitrates and carbonates, and phosphates or fluorides are introduced according to the requirements of the formulation. In order to ensure the transparency of glass, the content of colored impurities, such as iron, chromium, copper, manganese, cobalt, nickel, etc., must be strictly controlled. When ingredients are required, accurate weighing and uniform mixing are required.
Its main production process is smelting, forming, annealing and inspection. Then the specific steps are as follows:
① There are single crucible batch smelting method and tank kiln (see kiln) continuous smelting method for smelting. Single crucible smelting method can be divided into clay crucible smelting method and platinum crucible smelting method. No matter what kind of smelting method is used, it needs to be stirred with a stirrer, and the temperature and stirring are strictly controlled to make the glass liquid reach a high degree of uniformity. The clay laser focusing mirror crucible can melt most of the crown glass and flint glass, with low cost, and is used when the melting temperature of the glass exceeds the service temperature of platinum. The platinum crucible can smelt high-quality glass that has a serious corrosive effect on the clay crucible, such as heavy crown, heavy barium flint, rare earth glass and fluorophosphorous glass. The platinum crucible is heated by electricity, generally a silicon-carbon rod or silicon-molybdenum rod electric furnace is used. However, high-frequency heating can be used to manufacture glass that has a high tendency to crystallize, requires rapid cooling, and has certain requirements on the atmosphere.
②The molding methods for molding optical glass include the classical crucible method, the rolling method and the pouring method. However, leakage molding (using a single crucible or Continuous melting and flowing out of the material liquid), can directly draw the rod or drop material, or form a large-size blank by leaking the material, which improves the utilization rate and yield rate of the laser protective mirror of the gob.
③ Annealing In order to eliminate the internal stress of the glass to the greatest extent and improve the optical uniformity, a strict annealing system must be formulated and precision annealing is performed.
④ The indicators for inspection and measurement include: optical constants, optical uniformity, stress birefringence, streaks, bubbles, etc.
The glass that can change the propagation direction of light and can change the relative spectral distribution of ultraviolet, visible or infrared light is called optical glass. It is an inorganic glassy material that transmits light through refraction, reflection, and transmission, or changes the intensity or spectral distribution of light through absorption. It has stable optical properties and high optical uniformity. Optical uniformity refers to the inconsistency of the refractive index of each point in the same piece of glass, which is caused by the unevenness of the laser collimator at various temperatures in the annealing furnace. When light passes through a piece of glass with uneven refractive index, it will cause irregular changes in the optical path of each part, thus affecting the imaging quality of the optical system.
Lenses made of optical glass are called optical lenses. So how to determine the quality of optical lenses? Let’s take a look at it together:
Light transmittance of the lens
Color optical lenses and aspherical ultra-thin optical lenses have better light transmittance.
The thickness of the lens
is related to the refractive power of the lens, the refractive index of the lens, the size and shape of the frame, and The interpupillary distance is related to the amount of shifting the center of light, related to the astigmatism axis, and related to the nature of the lens (concave and convex).
The weight of the lens
is related to the lens material, and the glass lens is heavier than the resin lens. The same lens material has a large specific gravity and a small specific gravity, and a large volume is heavier than a small volume (related to the lens power and shape size).
The hardness of the lens
Glass lens is harder than resin lens and is more wear-resistant.
The strength of the lens
The resin lens is stronger than the glass lens, and it is impact resistant and not fragile
The special function of the lens
such as anti-ultraviolet, anti-electromagnetic radiation, anti-infrared, high temperature resistance, oil resistance, acid and alkali resistance, anti-dispersion, anti-deformation (Ultra-thin aspheric lens), anti-glare and other functions. For example, the lenses for electric and gas welding, the lenses for computers, the lenses for underwater, and the lenses for fishing are different.