Design and error analysis of infrared dual-channel band pass filter with wide rejection band for detection application

In order to meet the requirements of high transmittance in pass bands, high reflectance in rejection bands, small ripple coefficient for detecting 1, 2-propanediol dinitrate with infrared detector cell, an infrared dual-channel band pass filter with proper rejection band has been designed using the combined method of the Herpin refractive index principle and local optimization, as well as choosing PbTe/ZnSe as the material of high/low refractive index. A dual channel filter with pass bands of 5.9~6.2 μm and 11.9~12.2 μm and the average transmittance exceeds 90% and 65% respectively was designed. An error analysis of layer physical thickness and refractive index has been done for the design, which shows that the precision of deposition rate should be controlled within 3.5%, meanwhile, the refractive index accuracy should be lower than 3%, the refractive index has greater effect on the reflectance than the thickness, and the double half-wave film is more sensitive in the changes of refractive index and the thickness.