The Design And Preparation Of The Filter Which Is Used To The Multi-wavelength Laser Damage Tester

Optical thin film components are important and vulnerable in the high power and large energy laser systems. Once the optical coatings are damaged by laser, the quality of beam will be reduced, and the whole optical system will even be broken. However, there are no effective testing methods and means to measure the laser-induced damage threshold(LIDT) of optical coatings. Therefore, it’s important to study the laser damage evaluation and LIDT detector. Based on this background, the multi-wavelength of laser damage detector need a suitable filter to work. The filter in the detector need to be designed and prepared.The LIDT and preparation technology of monolayer thin films are studied. Based on the above consequences, the coating materials are selected.The filter’s construction and its electric field intensity (EFI) is optimized. The filter is prepared by thermal evaporation technique. And the filter is irradiated by laser beam and electron beam which parameters are adjusted, the influence of these irradiation experiments are discussed. The results show that:1. LaTiO3 films are prepared by thermal evaporation technique. The results show that LaTiO3 films have stable optical performance and high LIDT. LaTiO3 films’ preparation technology parameters are optimized, when the deposition temperature is 175℃, the pressure is 2.0 x 10-2 Pa, electron beam current is 120 mA (8Kev), LaTiO3 film’s LIDT is 16.9J/cm2. The LIDT of LaTiO3 films is higher than that of TiO2, Ta2O5 and HfO2 films with the value of 46.19%,18.18%,28.42% respectively.2. SiO2 films are prepared by thermal evaporation technique.The results show that SiO2 films have good physical and chemical properties and a high LIDT. SiO2 films are prepared with oxygen gas which have a higher LIDT.The LIDT is 15.38% higher than that of other SiO2 films without oxygen. The preparation technology parameters are optimized:the pressure is 175℃,the deposition vacuum degree is 1.5 x 10-2 Pa,electron beam current is 30 mA(8Kev), the LIDT is 24.1J/cm2.3. The filter is designed by a TFCalc software. LaTiO3 and SiO2 are selected as the high and low refractive index materials. The filter model which is optimized is G|(HL)10H0.5L|A. The filter’s transmittance and LIDT are tested, the results show that the transmittance of sample is T532nm= 94.76%, T1064nm= 0.81%, and the LIDT is 11.7J/cm2.4. The filter is irradiated by laser beam and electron beam. The results show, when the laser irradiation energy is 80% of filter’s LIDT, the filter’s LIDT is 22.2% higher than that of an original one.When the variable is irradiation times, the filter’s LIDT has a significant improvement, which is 12.6% higher than original’s LIDT. When the filter is irradiated by electron beams, the LIDT will be reduced.