粮食筛选系统中双通道带通滤光膜的研制

Abstract

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 bandpass 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.