Fabrication of a Composite Film Optic with High Transmittance in Vis and IR Regions for an Optical System

In this study, a lightweight composite polyimide film optic with antireflective coating was prepared using an ion-beam-assisted reactive sputtering method. It exhibited high transmittance in visible (87%, 0.5~0.8 μm), short (86%, 1.8~2.7 μm) and middle (78%, 3.3~5.4 μm) wavelength infrared regions. Additionally, it also showed great optical homogeneity (0.006 λ in RMS and 0.034 λ in PV, λ = 632.8 nm) with smooth surfaces (RMS = 0.786 nm). The thermal stability of the polyimide film was also effectively maintained after the antireflective coating. At the same time, by utilizing the hydrophobic properties of coating materials (Ta2O5/SiO2), the antireflective layer acted as an effective water barrier on the film surface to reduce the water absorption.