Optical films can be divided into reflective film, anti-reflection film/anti-reflection film, neutral beam splitter (splitter), cut-off; filter, bandpass filter, polarization beam splitter according to their use classification, characteristics and application Filter, depolarizing film system, etc.
The selection of optical film is mainly divided into two steps:
1 Look at the wavelength
Different wavelengths of light are different, we need to be clear about which wavelength range of light we are studying
2 Look at the function
- 2.1 Anti-reflection film and high-reflection film
Anti-reflection film is also called anti-reflection film, AR film, AR film, anti-reflection film, AR filter. Its main function is to reduce or eliminate the reflected light of optical surfaces such as lenses, prisms, and plane mirrors, thereby increasing the transmission of these elements. Light quantity, reduce or eliminate the stray light of the system.
The high-reflective film is an optical element that is coated with a thin film on the back of the optical glass through a vacuum coating to reflect incident light. High-reflection films are divided into two types: medium high-reflection films and metal high-reflection films.
- 2.2 Neutral beam splitting membrane
The function of the neutral beam splitter: It can divide a beam of light into two beams of exactly the same spectral composition in a certain wavelength range, that is to say, it has the same transmittance and transmission rate for each wavelength within a certain wavelength range. The reflectance ratio (that is, the transmittance to inverse ratio), therefore, the reflected light and the transmitted light have no color—the color is neutral. The neutral beam splitting film is divided into a medium neutral beam splitting film, a polarized neutral beam-splitting prism, and a metal neutral beam splitting mirror.
- 2.3 Cut-off filter
The cut-off filter refers to a filter that can filter out all the long waves or short waves from the composite light and only retain the required wavelength range. Generally, the cut-off filter that suppresses the short-wave region and transmits the long-wave region is called the long-wave pass filter, and the cut-off filter that suppresses the long-wave region and transmits the short-wave region is called the short-wave pass filter.