Bandpass Filters
(i)Narrow Bandpass Filters
(ii)Long Bandpass Filters

A bandpass filter has a transmission band surrounded by two blocking bands that allow only a portion of the spectrum to pass. The characteristics of the bandpass are controlled by multilayer dielectric coatings. Blocking is usually achieved with a combination of color filter glass and specially designed metallic films. The bandpass and blocking elements are laminated (epoxied) together to form a single unit and then edge sealed to prevent degradation due to moisture.