双色滤光片的膜系设计方法有多种，如自动优化设计、缓冲层和组合膜系设计、加厚间隔层的Fabry-Perot(F-P)膜系、双峰结构F-P 膜系的多次重复，以及具有分形结构的F-P 膜系设计等方法。但它们在特定通道带宽和通道间距要求的膜系设计中，或者在膜系的工艺可实施性方面存在一定的局限性。运用目标光谱拟合优化后的两个具有增透带的F-P 膜系相组合的设计方法，有效解决了较宽通道带宽和较大通道间距的双色滤光片的设计问题。采用Ge和SiO 两种材料，利用有限的38层薄膜，在中波红外波段设计出了波形良好的双色滤光片，其两个通道的相对带宽均为9%，两个通道中心波长位置比可以在1.4~5.0 的范围内进行调整，通带边缘陡度不大于2.0%。这种膜系结构的双色滤光片具有通带宽度和位置方便调控的特点，并有较强的可实施性。

There are several methods to design dual-band-pass optical filters, such as automatic optimization, design using buffer and combinatorial layers, F-P filter with thick spacer layers; repeating blocks of F-P filter with double peaks and F-P filter with a fractal structure, etc. But they have certain limitations either in design that has specific requirements on band-width and distance between two channels, or in the technique implementation of the film stack. Using the method of combining two F-P filters with a transmission band, which is obtained from optimization of target fitting, the problem of designing a wide band-width and large channel span dual-band-pass filter is effectively solved. Using the materials of Germanium and Silicon monoxide, a good spectrum performance dual-band-pass optical filter is designed with a layer number of 38. The relative band-width of both path-bands are 9%, the ratio between two channels’wavelength position can be adjusted from 1.4 to 5.0, the steepness of all the band edges are no more than 2.0%. This kind of coatings structure has strong technological practicability as well as good adjustability of both pass-band-width and channel position.