A solution to adhesion problem of oxide thin films on Zinc Selenide optical substrates

Zinc Selenide optical substrates have high transparency within the 0.5 to 14.0 μm wavelength range. This makes them an attractive candidate for multi band imaging applications in the optical components. In order to minimize reflection losses for visible, near-infrared and mid-infrared applications, Zinc Selenide lens are coated with multi-layered oxide thin films by physical vapor deposition method or Ion Beam Deposition. In this study, four-layer dual beam anti-reflective coating design at 1.064 μm and between 3.6 and 4.9 μm is applied using Ion Beam Deposition system directly on Zinc Selenide substrates. Because of solving the adhesion problem which is observed after the coating of oxides on Zinc Selenide substrates, they were treated at 300 °C for varying amounts of time before coating oxides. Treated samples were examined in terms of their roughness, contact angle, morphology, refractive index, transparency, crystallography and chemical composition. It is found that it is possible to manufacture durable oxide thin film coatings on Zinc Selenide, utilizing well designed pre-treatment processes.