The Research Of Spectrum Analysis Filter In The Ultraviolet Alarm System

In this thesis, both theoretical and experimental investigations of the ultraviolet spectrum analysising filters are given. The main works are design and fabrications of the filters which can meet the need of the ultraviolet alarm detection systems.The thesis describes the development and the current status of the UV filters of the alarm detection systems. A research on the principle of the solar blind ultraviolet alarm detection systems was done. The characteristic matrix of the film derives from the basis of Maxwell equation which was utilized to analyzing antireflection film theory of the single-layer film and multilayer films. Theoretical model of the multilayer interference cut-off filter was established.The materials chosen were hafnium oxide (HfO2), magnesium fluoride (MgF2) and ultraviolet silicon dioxide (UV-SiO2) which were used as coating materials and JGS1used as the substrate according to the study of the material properties. Electron beam heating method (EB) was coating the ultraviolet filters by choosing appropriate technological parameters. The problem of the accuracy controlling the film thickness was solved by the combinations of quartz crystal oscillation and optical extremum method, and ion assisted deposition (IAD) was utilized to improve the film density.The filters could meet the demand of high transmittance range from240nm～280nm at an angle of incidence from0°～25°. At wavelength from300nm～620nm, the filter can act as suppression filter. The problem of film stripping, absorption of material and other issues are solved. Finally, the thesis summarized the main works and the major achievements, and proposed the further research of the optical filter.