Research on optical non-uniformity and stability of TiO2–SiO2 glass

Abstract

The shape and value of optical non-uniformity are of great significance to optical materials and directly determine whether optical materials can process into finished components in optical systems. TiO2– SiO2 glass is usually used to prepare high-precision lightweight space mirrors and large-scale ground-based telescopes due to its low expansion. The corresponding relationship between the surface shape change and the temperature change of the glass prepared by CVD process needs to be verified. The shape of the silica glass with different doping contents is manufactured to 50×8 mm, and the surface shape of samples is polished to about 0.5λ (λ=632.8 nm). A ZYGO laser plane interferometer with a 100 mm aperture is used to test the samples' optical non-uniformity values and optical stability under the rapid change of temperature. The results show that the doping of TiO2 can significantly improve the optical stability of silica glass. When the sample is rapidly cooled from 80 to 20 , the change rate of PV value is only 0.01~0.02λ (λ=632.8nm). The morphology and numerical value (Δn=10ppm) of optical inhomogeneity can be used as optical transmission materials. Silica glass doped with 7.5-10wt% TiO2 has good optical stability, and the transmittance of visible light and near-infrared light is greater than 90%. Its optical inhomogeneity is in the order of 10-5, and its morphology has no apparent mutation. Therefore, it can be used as a reflective material and as a transmissive material in optical systems.