The Study On The Preparation And Rapid Aging Of Silica Antireflection Film

Antireflective films are widely used in optical engineering fields due to their high transmittance,laser damage threshold,simple preparation process.In this thesis,Silica colloids with different particle sizes were prepared by alkaline route,and Silica antireflection films（called"SiO₂ antireflection films"）were prepared on fused silica substrate by dip coatings method.The SiO₂ antireflection films were modified with ammonia and hexamethyldisilazane（HMDS）to promote the rapid aging and enhance contamination and hydrophobicity resistance of SiO₂ antireflection films.By optimizing the post-treatment parameters of SiO₂ antireflection films,the excellent SiO₂ antireflection films were obtained.The main research contents and conclusions are as follows:Silica colloids with different diameters were prepared by sol-gel method.The results showed that the size of colloidal particles increased first and then decreased with the increase of deionized water,and increased with the increase of ammonia and tetraethyl orthosilicate（TEOS）.For the SiO₂ antireflective films prepared by dip coating method using colloidal particles with different size.The smaller the particle size is,the higher the transmittance is.We chose the SiO₂ antireflection films which prepared on fused silica substrate by dip coating method with colloid with particle size of 29 nm as research objects.The prepared SiO₂ antireflection coatings were treated with ammonia water,hexamethyldisilazane（HMDS）,ammonia water followed by HMDS（ammonia-HMDS treatment）and HMDS followed by ammonia water（HMDS-ammonia treatment）,respectively.By comparing the four treatment methods,it is concluded that ammonia-HMDS post-treatment can not only accelerate the aging of SiO₂ antireflective film,but also make the treated SiO₂ antireflective film maintain excellent optical properties and good contaminant and hydrophobicity resistance.Ammonia-HMDS treatment method was used with adjusting the temperature and time of post-treatment to further optimize the aging parameters of SiO₂ antireflection films.The results show that a good modification effect of SiO₂ antireflective film has achieved when the post-treatment time exceeds 24 h.When the post-treatment temperature does not exceed80℃,the treated SiO₂ antireflective films not only has excellent optical properties,but also has significantly improved contaminant and hydrophobicity resistance.However,when the post-treatment temperature is higher than or equal to 80℃,not only the integrity of SiO₂antireflection coating is damaged,its optical properties also reduced.The laser damage threshold of SiO₂ antireflective films were tested after the two-step post-treatment of ammonia-HMDS.The results show that the laser damage threshold of SiO₂antireflection coating treated with ammonia-HMDS is 22.3 J/cm²,which is slightly lower than that of untreated SiO₂ antireflection film of 24.3 J/cm²,indicating that SiO₂antireflection films still have high laser damage threshold after two-step treatment.It can be concluded that:the aging films,which have excellent optical properties and high laser damage threshold,can be obtained by ammonia-HMDS modification for 24 hours in the temperature of 20～50℃.The experimental results in this paper can provide a reference for the application of antireflection films in optical engineering.