Spectral band: UV filter, visible filter, infrared filter;
Spectral characteristics: band pass filter, cut-off filter, spectroscopic filter, neutral density filter, reflection filter;
Film material: soft film filter, hard film filter;
Dural filter not only refers to the hardness of the film, but also its laser damage threshold, so it is widely used in laser system, while soft film filter is mainly used in biochemical analyzer.
Band pass type: light passing through the selected band and light cut off outside the band. The main optical indexes are center wavelength (CWL) and half bandwidth (FWHM). It is divided into narrowband and broadband. For example, narrow band 808 filter nbf-808.
Short wave pass (also known as low wave pass): light passing through shorter than the selected wavelength, and light cut-off longer than the wavelength. For example, infrared cut-off filter, ibg-650.
Long wave pass (also known as high wave pass): light longer than the selected wavelength passes through, and light cut-off shorter than the wavelength, such as infrared transmission filter, ipg-800.