The refractive index of optical glass will take you to explore high-precision optical instruments

by:Crylight     2021-05-07

Optical glass is different from ordinary glass. It is a high-quality glass that can be used to make optical lenses. It is also the main basic material for optical instruments, such as telescopes and fisheye lenses. At present, the development of optical glass has been closely integrated with the development of optical instruments and is inseparable. With the improvement of optical technology, optical glass is constantly being put forward new requirements. What is the refractive index of optical glass?

Compared with general glass, optical glass is produced with a small amount of special materials, such as light-sensitive materials AgCl, AgBr, etc., and a small amount of sensitizers such as oxidation Copper etc. Adding a small amount of these substances can make the glass extremely sensitive to light. In addition, there are two other characteristics that optical glass must possess, that is, exceptionally accurate refractive index and extremely high-precision Abbe number. In addition, there are extremely high requirements for transparency and uniformity. Here, I will give you a brief explanation on the refractive index of optical glass.

The refractive index of glass is the ratio of the speed of light propagating in vacuum to the speed of light propagating in this type of glass, which is a characteristic of glass. As a high-quality glass, each specific optical glass has a specified standard refractive index value for a certain wavelength of light. This is a necessary condition for optical glass, because it is designed by optical designers. The basic conditions of optical instruments. If the refractive index of optical glass does not meet the standard, the optical instruments manufactured by this optical glass will deviate once they are used, or cannot achieve the expected imaging effect. This is absolutely intolerable in the research field. of.

In the manufacture of optical instruments, there are strict requirements on the accuracy of the refractive index of the optical glass, which requires the refractive index error of the optical glass manufactured in the same batch to be within a certain range Within, of course, the smaller the error, the better. This is conducive to the calibration of the instrument. In the actual use of optical glass, there is another important indicator, that is, optical uniformity, which refers to the inconsistency of the refractive index of the same light at different positions in the same piece of glass. This is because the glass produced In the process, a phenomenon caused by the inconsistency of temperature in different places in the annealing furnace. When a beam of light passes through a piece of glass with non-uniform refractive index, the path of the light will show irregular changes, and the optical instrument will show undesirable imaging quality.

Optical classification:

Colorless optical glass

There are specific requirements for optical constants, with high transmittance in the visible region, no Select the characteristics of absorption and coloring. According to the size of Abbe number, it is divided into coronal type and flint type glass, and each type is divided into several types according to the refractive index, and they are arranged in order according to the refractive index. Mostly used as lenses, prisms, mirrors, etc. of telescopes, microscopes, cameras, etc.

Radiation-proof optical glass

It has a large absorption capacity for high-energy radiation. There are high-lead glass and CaO-B2O2 system glass. The former can prevent γ-ray and X-ray radiation According to the photo, the latter can absorb slow neutrons and thermal neutrons, and is mainly used as a shielding and peeping window material in the nuclear industry and medical fields.

Irradiation resistant optical glass

Under certain γ-ray and X-ray irradiation, the transmittance of the visible area changes less, and the varieties and grades are the same as colorless optical glass. Used to manufacture optical instruments and peep windows under high-energy radiation.

Colored optical glass

Also known as filter glass. It has selective absorption and transmission performance for specific wavelengths in the ultraviolet, visible and infrared regions. According to the spectral characteristics, it is divided into three types: selective absorption, cut-off and neutral gray; according to the coloring mechanism, it is divided into ion coloring, metal colloid coloring and sulfur selenium There are three types of chemical coloring, which are mainly used in the manufacture of optical filters.

Ultraviolet and infrared optical glass

It has specific optical constants and high transmittance in the ultraviolet or infrared band, and is used as ultraviolet and infrared optical instruments or as window materials.

Optical quartz glass

Using silica as the main component, it has the characteristics of high temperature resistance, low expansion coefficient, high mechanical strength, and good chemical properties. Through prisms, lenses, windows and mirrors with special requirements. In addition, there are also photomasks, liquid crystal display panels, and thin-plate glass used in the manufacture of large-scale integrated circuits; magneto-optical glass in which the polarization plane rotates when light passes through the glass along the direction of magnetic force; light is transmitted in a certain direction Acousto-optic glass with light diffraction, reflection, convergence or light frequency shift occurs when ultrasonic glass is used.

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