Bandpass Filter is optical filter that passes one or more specified wavelength bands while blocking other wavelength bands. Bandpass Filter refers to wavelength ranges and is also called passbands. It is designed to transmit specific wavelength bands. They are common filters suitable for a wide range of optical applications, including: environmental testing, chromaticity measurement, flame photometry, fluorescence applications, ultraviolet sterilization, spectral radiation measurement, medical diagnosis, chemical analysis, machine vision, biotechnology instruments and medical treatment. There are many types of Bandpass Filter and each has its advantages.
Bandpass Filter can only transmit specific wavelength bands and block other wavelength bands. The width of this filter is expressed in the wavelength range that allows it to pass and it ranges from a few nanometers to hundreds of nanometers. This kind of filter can be manufactured by combining a long-pass filter and a short-pass filter.
Bandpass Filter is defined by three key characteristics:
Center Wavelength (CWL)-the wavelength at the center of the passband.
Half Bandwidth (FWHM)-The bandwidth is 50% of the maximum transmission.
Peak transmittance (T)-wavelength of maximum transmittance.