Optical glass refers to glass that can change the transmission direction of light and the relative spectral dispersion of ultraviolet, visible or infrared light. Optical glass in a narrow sense refers to colorless optical glass; Optical glass can be used to make lenses, prisms, mirrors and windows in optical instruments. The difference between optical glass and other glasses is that as a component of optical system, it must meet the requirements of optical imaging. Therefore, the determination of the quality of optical glass also includes some special and strict indicators.
1、 Specific optical constants and consistency of optical constants of the same batch of glasses.
Each type of optical glass has a regular standard refractive index value for different wavelengths of light, which serves as the basis for optical planners to plan optical systems. Therefore, the optical constants of the optical glass produced by the factory must be within a certain allowable error range of these values, otherwise the actual imaging quality will be inconsistent with the expected results in the planning and the quality of optical instruments will be affected.
2、 High transparency.
The brightness of the optical system image is proportional to the transparency of the glass. The transparency of optical glass to light of a certain wavelength is determined by the light absorption coefficient K λ express. After the light passes through a series of prisms and lenses, some of its energy is lost by the interface reflection of optical parts, and the other is absorbed by the medium (glass) itself. Therefore, for the optical system containing multiple thin lenses, the primary way to improve the transmittance is to reduce the reflection loss of the lens surface, such as coating the external antireflective film.
