Band Pass Filter

A band pass filter is a device that passes wavelenths within a certain range and rejects (attenuates) wavelengths outside that range. The working range could be ultraviolet, visible, near infrared, far infrared, optical communication depending on the need of designed optical system. The band pass filter is more difficult product in coating thin films than ordinary AR, IR, dichroic filter. It have to precisely control two locations of T50% in left and right shoulder of spectrum curve. Both in spectrum desing and producing operation, control two points is more difficult to control one points.