Long wave pass filter divided into two categories: one, by photochemical absorption wavelength is absorbed ingredients to make the short and long wave length through the filter, features: easy processing and low cost. Second, the coating type coating method is to make short-cut through the media by longwave Features: a large steepness, as deep, high transmittance and optical density characteristics, but also by the angle to change the mobile wavelengths in applications in tune to your desired wavelength. Optical parameters: the wavelength error +/- 2nm by more than 90% cut-off wavelength band of less than 1%