Research On The Reflectivity Measurement Method For The Surface With Micro-Nano-scale Periodic Structures

In this dissertation, the method to measure the reflectivity of the surface with micro-nano-scale anti-reflection structures in one and two dimensions has been researched. The aim is to resolve the measurement problem emerged in manufacturing process of the new type of anti-reflection structure surface. The results could be provide the theoretical and experimental basis to support the applications of micro- nano-scale anti-reflection structures on the surface of large outdoor facilities such as solar cell surface to enhance the conversion efficiency, or on the optical components surface in the strong power laser system to resist damage, etc.Generally the anti-reflection micro-nano-scale structures fabricated by optical lithography technology are one and two dimensional grating, or the array of dots or holes. Compared with the traditional anti-reflection optical component, the one and two dimensional periodic structures performe different optical properties, so it is necessary to study the measurement method specially for the reflectivity of this new type of anti-reflection periodic structure. In this dissertation, the reflection characterisics of micro-nano-scale periodic structure has been studied, the factors impacted on the reflectivity has been analyzed, the measurement system scheme has been given.Firstly, the optical element reflectivity measurement methods have been investigated based on lots of literatures, and the limitation of currently measurement system for micro-nano-scale anti-reflection structures has been studied.Secondly, the expressions of reflectivity of sub-wavelength grating surface are deduced by effective-medium theory combined with optical thin film theory. Some optimal parameters of one dimensional rectangular anti-reflection grating are obtained through the calculation and simulation of sub-wavelength anti-reflection grating. The results indicated that the influence factors of the reflectivity of periodic micro-nano-scale structures include incident angles, etched depth, filling factor and grating period.Based on theoretical research, the reflectivity measurement system scheme has been suggested for micro-nano-scale anti-reflection structures, the optical system and the selection of devices have been introduced. The experimental system has been built. The wavelength range of system are 400-800nm, the samples are a holographic diffraction gratings with 3600 lines/mm and a ruled diffraction grating with 1800 lines/mm. The multi incidence angle and azimuth angle experiments have been finished. The experimental results show that the reflectivity change trends by experiments are met the expected results by theoretically.