Classification of filter products

        There are many types of optical glass, and filter is one of them, which can change the direction of light propagation. Filters are widely used in lenses, prisms, etc. of optical instruments. The optical filter must meet the requirements of optical imaging, so the quality of the optical filter is very high.

        There are two types of filters for installation and use. One is the colored or colorless optical glass used on the lens, which can be called a filter. This filter can be divided into: black and white photography filter, color photography filter color, black and white photography shared filter, special effect filter. The other is the flash filter used in front of the flash, which is used to adjust the color tone of all or part of the subject to produce a special color.

        Filter products are mainly classified by spectral band, spectral characteristics, film material, application characteristics, etc. Specifically, it can be divided into the following categories:

        Spectral band: UV filter, visible filter, infrared filter;

        Spectral characteristics: bandpass filter, cut-off filter, spectroscopic filter, neutral density filter, reflection filter;

        Film material: soft film filter, hard film filter;

        Bandpass type: Light in the selected band is passed, and light outside the passband is cut off. Its optical means, mainly center wavelength (CWL), half bandwidth (FWHM). Divided into narrowband and broadband. Such as narrow band 808 filter NBF-808.

        Short-wavepass type (also called low-pass): Light shorter than the selected wavelength passes through, and light longer than the wavelength is cut off. Such as infrared cut filter, IBG-650.

        Long-wavepass type (also called high-pass): Light longer than the selected wavelength passes through, and light shorter than the wavelength is cut off, such as infrared transmission filter, IPG-800.