利用杂质和劣质粮食与优质粮食的近红外吸收光谱不同的特性, 根据光谱中反映测试成分的特征波段的差异对粮食进行光学分选.在光谱进入传感器之前经过滤光片对多个测试波段进行过滤, 降低噪音的影响.本文针对光学筛选系统中核心部件双通道带通滤光片进行研制, 从膜系设计理论出发, 采用了Smith法结合膜系设计软件设计了以周期膜系和非周期膜系相结合的双通道带通滤光膜系, 利用电子束蒸发和离子辅助沉积的方法进行制备并通过数学建模分析, 减小了实验误差对光谱的影响.在1 200 nm和1 450 nm波段得到平均透射率大于97%, 1 000~1 130 nm和1 570~2 000 nm波段平均透射率小于1%的滤光膜, 通过系统测试, 满足使用要求.

Optical sorting of grain, is using different characteristics of near infrared absorption spectra of impurity inferior food and high quality food, and based on the difference of feature band which reflects the test components in the spectrum to do the sieving grain. Before the light beam into the sensor, it needs to pass through the optical filter,filtering the multiple test band and reducing the noise effect. A dual band-pass optical filter was developed which is the core parts in the system, it is based on the film system design theory, adopt Smith method and the film system design software basing on the combination of period and non period multilayer coatings to design the dual band-pass filter coating,. Utilize electron beam evaporation and ion assisted deposition method to prepare and mathematical modeling to analyze, which has reduced the influence of experimental error to the spectrum and prepared the filter coating. The average transmittance of which is more than 97% in 1 200 nm and 1 450 nm band and less than 1% in 1 000~1 130 nm and 1 130~2 000 nm band. The film meets the use requirements through the test system and evaluation.