Tag - optical filters

A Brief Introduction of Optical Filters——Part Ⅱ Types of Optical Filters

There are different classification method of filters. It can be classified according to spectral band, spectral types, bandwidth, wavelength, features of coating, industry application etc. The following will introduce two common classification ways. 1.Classified according to spectral band According to the length of spectrum, filters can be divided into ultra violet filters, visible light filters, near infrared filters, infrared filters and far infrared filters. The wavelengths are listed as follows: Ultra violet filters—180~400nm Visible light filters—400~700nm Near infrared filters—700~3000nm Infrared filters—over 3000nm~10μm Far infrared filters—15~1000μm  2.Classified according to [...]

A Brief Introduction of Optical Filters——PartⅠDefination and Working Theory of Optical Filters

Filter is a kind of optical element with selective absorption of different bands of light. It is made of plastics or polished and coated glass. Generally, red filters can only pass through red light. The transmittance rate of glass is almost the same with that of air, so all coloured light can pass through. But after dyeing, the molecular structure of glass will change, the refractive index will change either, which influence the transmission of certain coloured light. For [...]