Research On Blue Light Protective Film

Due to the frequent use of electronic devices,it brings a huge burden to the human eye.Among them,blue light is the highest energy part in the visible light band and has the greatest damage to the human eye.In order to reduce the damage of blue light to the human eye and reduce the burden on people’s eyes,this paper takes blue light protective film as the research object,and uses optical film theory combined with TFCalc software to design two kinds of blue light protective films with different harmful blue light transmittance,which are cut-off blue light protective film and semi-cut-off blue light protective film.According to different application scenarios,the visible light broadband antireflection film was matched and designed,and the film preparation and testing were completed by using electron beam evaporation coating machine and spectrophotometer.The main contents are as follows:First,a visible light broadband antireflection film was designed by TFCalc software.The substrate is K9 glass,the center wavelength is 520 nm,and the high and low refractive index materials are Ta₂O₅and Si O₂,respectively.The average transmittance in the visible light band is 97.86%.Through simulation,it is concluded that when the refractive index error range of Ta₂O₅is-0.2～-0.1,and the refractive index error range of Si O₂is-0.1～+0.1,the average transmittance of the visible light broadband antireflection film is not less than 97.5%,achieving better antireflection effect.Second,the simulation of the cut-off blue light protection film shows that when the refractive index error of TiO₂and Si O₂in the whole band changes from-0.2 to+0.2,the spectral curve shows obvious red shift.When the refractive index error of TiO₂in the whole band is controlled between-0.2 and 0,the transmittance of 415～445 nm band is lower than42%,the transmittance of 445～475 nm band is greater than 80%,and the transmittance of475～505 nm band is stable at 96%,which meets the design requirements.The transmittance of the beneficial blue light in the 445～475 nm band can reach more than 80%of the new national standard when the refractive index of Si O₂changes from 0 to+0.2.Therefore,the refractive index error of Si O₂should be controlled between 0 and+0.2.Third,using TFCalc software,a semi-cut-off blue light protective film was designed.The center wavelength is 550 nm,the substrate is K9 glass,and the high and low refractive index materials are TiO₂and Si O₂,respectively.The film system can shield 57.5%of the harmful blue light.The average transmittance in the 445～475 nm band is 81.8%,and the average transmittance in the 475～505 nm band is 98.9%,which can effectively shield the harmful blue light and reduce the color difference of the object.Through simulation,it is concluded that when the refractive index error of TiO₂is controlled between-0.2and-0.1,the average transmittance in the 415～445 nm band is less than 56%,the average transmittance in the 445～475 nm band is greater than 81.8%,and the average transmittance in the 475～505 nm band is greater than 99%.When the refractive index error of Si O₂is controlled between+0.1～+0.2,the average transmittance of 415～445 nm band is less than 65.5%,the average transmittance of 445～475 nm band is more than 80%,and the average transmittance of475～505 nm band is more than 93.8%,which meets the design requirements of moderate cut-off of harmful blue light.Fourth,single-layer TiO₂,Ta₂O₅and Si O₂films with center wavelength of 550 nm were designed by TFCalc software,and single-layer TiO₂,Ta₂O₅and Si O₂films were prepared by electron beam evaporation technology.The influence of key process parameters such as ion source current,oxygen flow rate and deposition rate on the refractive index of single layer film was studied by controlling a single variable.The transmittance spectra of TiO₂and Ta₂O₅monolayers and the reflectance spectra of Si-based Si O₂monolayers were measured by Shimadzu UV-Vis-NIR spectrophotometer.The refractive index of the material was fitted by spectrophotometry.The dispersion curves of the three materials were obtained.The influence of different experimental processes on the refractive index of each monolayer was obtained by analysis and comparison.The results show that:For single-layer TiO₂and Ta₂O₅films,the refractive index increases gradually when the ion source current increases gradually in the range of 1～3 A.For single-layer Si O₂films,the refractive index increases first and then decreases when the ion source current increases gradually in the range of 1～3 A.When the ion source current is 2.5 A,the refractive index reaches the maximum.For single-layer TiO₂and Ta₂O₅films,when the oxygen flow rate increases gradually in the range of 10～30 sccm,the refractive index decreases first and then increases.When the oxygen flow rate is 20 sccm,the refractive index of TiO₂is the largest.When the oxygen flow rate is 15 sccm,the refractive index of Ta₂O₅is the largest.For single-layer Si O₂films,when the oxygen flow rate increases gradually in the range of 4～8 sccm,the refractive index increases first and then decreases.For single-layer TiO₂and Ta₂O₅films,the refractive index gradually increases when the deposition rate gradually increases in the range of 0.15～0.35 nm/s.For single-layer Si O₂films,the refractive index gradually increases and then remains unchanged when the deposition rate gradually increases in the range of 0.4～0.8 nm/s.The refractive index of Si O₂reaches the maximum when the deposition rate is 0.8 nm/s.Fifth,the visible light broadband antireflective film,cut-off type and semi-cut-off type blue light protective film were plated by electron beam evaporation technology.The surface and cross-section morphology of the three films were observed by scanning electron microscope.There were no obvious defects in the internal structure of the film.The dielectric layers were tightly bonded,the surface was smooth and the density was good.The spectral curves of the three films were obtained by Shimadzu UV-Vis-NIR spectrophotometer.The average transmittance of 380～780 nm is 96.94%.The cut-off blue light protective film can achieve an average transmittance of 19.2%in the 415～445 nm band,an average transmittance of 80.4%in the 445～475 nm band,and an average transmittance of 92.8%in the 475～505 nm band.The semi-cut blue light protective film can achieve an average transmittance of 40.39%in the 415～445 nm band,an average transmittance of 80%in the 445～475 nm band,and an average transmittance of 95.6%in the 475～505 nm band.The experimental results of the films are consistent with the theoretical design and reach the expected index.