How do optical lens manufacturers make optical lenses? (2)
Description of raw materials of optical lenses
The lens materials selected by optical lens manufacturers are transparent media, mainly divided into inorganic and organic. There are two main categories. In our daily life will also encounter a natural medium crystal lens, which is made of quartz ore grinding lens. Ancient crystal can raise colour bright eye, but in fact the main composition of crystal is silicon dioxide (sio2), bigger advantage is high hardness, not easy be affected with damp be affected with damp, but ultraviolet and infrared transmittance is higher, and the crystal density uneven, with impurity, have stripes and bubble wait to produce, can form birefringence phenomenon, thus affect vision.
1, inorganic materials - glass
The glass used by optical lens manufacturers is right and wrong. An often special amorphous material that appears solid at room temperature, hard but brittle, and viscous at high temperatures. Glass has no fixed chemical structure and therefore no exact melting point. As the temperature rises, the glass material will become softer, more viscous, and gradually change from solid to liquid. This gradual change is called the "glassy state". This property means that glass can be machined and cast at high temperatures. Optical lenses made of glass have a non -. Good light transmittance, more transparent after surface polishing, cutting because of high hardness, easier processing molding, higher precision.
(1) Common glass materials (1.5 and 1.6) : Corona glass with refractive index of 1.523 is the manufacturing material of traditional optical lenses by optical lens manufacturers, of which 60%~70% is silicon dioxide, and the rest is mixed with calcium oxide, sodium and boron and other substances.
(2) High refractive index glass materials: After years of research, optical lens manufacturers have found a way to improve the refractive index of materials while maintaining low dispersion, namely adding new chemical elements to the glass. As early as 1975, titanium containing lenses were produced with a refractive index of 1.7 and an Abbe number of 41; Fifteen years later, a lanthanum-containing lens with a refractive index of 1.8 and an Abbe number of 34 was produced; In 1995, a material with a refractive index of 1.9 and the addition of the element niobium with an Abbe number of 30 appeared, which is currently the lens material with a higher refractive index. Widely used in the laboratory, the large enterprise R & D institutions used in the field of optical research and development, production.
