基于金属网栅结构设计的光学透明频率选择表面（FSS）加载于复合制导头罩的光学窗口时，其对红外入射光的衍射作用会干扰系统的成像效果。为了能够在光学透明FSS的设计过程中减少衍射带来的干扰，基于夫琅禾费衍射理论，研究了光学透明FSS结构参数变化对其衍射特性的影响。研究发现：当金属网栅周期增大或线宽减小时，衍射光强增加但分布无变化，其中周期对于光强的影响较为显著；随着十字FSS单元缝宽和缝长的增大，衍射光强增加而分布保持不变；此外，当入射光波长增大时，光学透明FSS的总透射率增加，与实验测试结果相符。上述规律将在光学透明FSS的实际设计过程中起到十分重要的指导作用。

Optically transparent frequency selective surface (FSS) is designed on metallic mesh. When it is loaded on the optical window of combined guidance radome, the diffractive effect to infrared will interfere with the quality of imaging system. For reducing the interference in the design procedure of optically transparent FSS, this paper specifically studies the influence of structural parameters of optically transparent FSS on the diffractive characteristics based on Fraunhofer diffractive theory. It is found that when the period of metallic mesh increases or the line width decreases, the intensity of diffractive light increases but distribution remains constant and the period has more notable influence on intensity. As the slit width and length of cross FSS unit increase separately, the diffractive light has rising intensity and unchanged distribution. Moreover, when the wavelength of incident light increases, the integral transmittance of optically transparent FSS increases. These show a good agreement with experimental results. The analysis mentioned above will have an important guiding significance in the process of designing optically transparent FSS.