Study On Deep Cut-off Solar Blind UV Interference Filter

Due to the absorption of atmospheric ozone, solar blind ultraviolet is formed withgood anti-jamming, good confidentiality, and solar blind ultraviolet filter becomes a keycomponent in the fields such as UV warning, UV imaging, UV communication. In order toimprove the Signal to Noise Ratio, it is necessary to research deep cut-off solar blind UVinterference filter. This topic is supported by the "973" plan "The study on wide spectrumof wireless signal transmission theory and method ","optical system noise and SNRoptimization method" to study solar blind UV filter.This paper mainly studies the design of deep cut-off solar blind UV interference filter,the characters of materials and the crafts of films.1. Solar blind UV interference filter is designed based on the theory of filmcharacteristic matrix, which the main transmittance of250nm-260nm is about83%and thedepth of280nm-600nm is about OD4, and analyzed in three aspects including sensitivity,layer sensitivity and monitor curve.2. According to the design and characters of materials, UV fused silicon JGS1isselected as the substrate and HfO2and SiO2are selected as the film materials. The constantsof JGS1are measured using the spectrophotometric method and the constants of HfO2andSiO2are measured with multilayer model by spectroscopic ellipsometry usingpoint-by-point method.3. The best parameters of UV films are studied using orthogonal experiments by ionbeam assisted deposited technology and electron beam evaporation technology in theZZSX-850coating machine, and the results are that the base pressure is3×e-3Pa, thedeposited pressure is2×e-2Pa, the temperature is250℃, the Oxygen flow is6sccm and thesize of ion beam is30mA. The same deposition rate of HfO2and SiO2is0.5nm/s and thetooling factors are78.4%and76.1%. A UV cutoff filter is made and the transmittancebetween250nm and260nm is up to60%. The study is a useful exploration of fabricatingUV interference filters.