In a certain band, there is only a small band with high transmittance in the middle and a high reflectivity cut-off band on both sides of the band. This kind of optical filter is collectively called band-pass optical filter. Its main function is to select the spectrum of light, so that the required light passes through, the light cut-off of unnecessary wavelength. At present, bandpass optical filters are widely used as optical components for filtering and selecting spectral lines.
What are the factors that affect the price of band-pass optical filters?
First, the central wavelength, the peak wavelength, generally speaking, the higher the transmittance, but not necessarily, in the ultraviolet band of biological instrument filters do not need this high transmittance.
Second, the cut-off depth of band-pass optical filters,
the better the cut-off depth is, the better the effect of clutter on induction components can be shielded, which will make the optical induction elements respond to more accurate signals.
Third, the bandwidth, the bandwidth can not be said to be good or narrow, but generally speaking, in bandpass optical filters, the higher the transmittance, the narrower the bandwidth, and the lower the cut-off depth OD value. However, the production process of such bandpass optical filters has become more expensive.
Other optical characteristics of band-pass optical filters:
The higher the cut-off OD value is, the narrower the pass bandwidth will be. At the same time, the higher the reflectivity of the cut-off film is, the larger the absorption and scattering will be, so the peak transmittance of the band-pass optical filter will be lower. In all-dielectric band-pass filters, if the transmittance of the two layers is not equal, the pass-band transmittance of the filters will also be affected.