IR Cut-off Film of Target Microsttucture Surface Scattering Parameters

To assist to research on a microstructure scattering parameters, reflect 1064nm wavelength and make visible light through target surface, an infrared cutoff filter is proposed. In order to enhance the laser damage threshold and optimize the distribution of the temperature field, based on the parameters requirements and thin film electromagnetic field theory, and were used as coating materials, a merit function was built, and a film was designed in which the electric field intensity was lower and reflectivity was higher, through the simulated annealing algorithm. Electron beam heating evaporation and an ion-assisted deposition system were adopted in film preparation. By simulating curve, the functional monotonicity of the reflectivity was studied. It was determined that the ratio between high and low index material has an impact on the equivalent refractive index function and reflectivity. Through adjusting the high film sensitive thickness, the film mismatching issue was solved. The average transmittance between 380nm and 780nm was more than 97.2%, the average reflectance in 1150± 20nm was more than 99.99%, and the average reflectance in 1270± 20nm was more than 99.99%. It is shown that the infrared cutoff filter can meet the requirements of environmental testing, and has a high laser damage threshold.