Study On The Anti-Reflective Surface Of Moth Eye With Infrared Substrate Composite Structure

The surface of antireflective micro-nano structure has excellent optical properties of wide spectrum and wide angle antireflection,which has broad application prospects in the field of photocell and optical detection.However,with the increasingly extensive research and application of micro-nano structured surface,in order to control the wavefront distortion of the target light field,the structural units usually have sub-wavelength structural characteristics,and have a high structural aspect ratio.The small size and high aspect ratio of the periodic structural elements make the surface of micro-nano structure is damaged by external environment and its optical performance is affected.In order to enhance the mechanical stability of the micro-nano structure surface and extend its service life,this paper proposes an anti-reflective micro-nano structure surface with a silicon oxide composite grid structure based on monocrystalline silicon.The antireflective micro-nano structure is located at the lower layer of the composite grid and protected.Its advantage is to improve the mechanical stability of micro-nano structure without changing the design and optical properties of the micro-nano structured surface.Analyze the optical and mechanical properties of composite grids in terms of material morphology,structural parameters.Using finite element analysis software to simulate and model triangular grid structure,square grid structure and hexagonal grid structure,it is found that under the same periodic structure and grid width conditions,the compressive capacity of hexagonal grid structure is 16.3% higher than that of square grid structure,and 11.7% higher than that of triangular grid structure.The results show that hexagon has the best compression resistance.Based on this theoretical analysis,the hexagonal composite grid antireflection micro-nano structure was prepared and its optical properties were tested.The optical antireflection surface of the micro-nano structure with composite grid structure was fabricated using a combination of proximity photolithography and nanosphere photolithography.The morphology of the composite grid antireflection micro-nano structured surface by SEM is good,the average reflectance of the composite grid anti-reflective micro-nano structure surface in frequency band of 3-5 μm is less than 4% at the incident angle of 8°～40°and the anti-reflection performance is stable.Furthermore,the average reflectivity difference between the anti-reflective moth-eye structure surface with composite grid and the single moth-eye structure surface is 0.068%,which can prove that the grid structure has little effect on the optical performance of the overall structure.Finally using the optical film firmness testing method,the adhesive tape is peeled off from the composite grid anti-reflection moth-eye structure surface and the moth eye structure surface without grid structure.The test results showed that the morphology of the moth-eye structure surface protected by the grid structure remained good and the anti-reflection performance did not significantly change after the adhesive tape was removed.However,the surface of the moth-eye structure without grid was damaged and the reflectivity increased by 1.5% after the adhesive tape was removed.It can be proved that the grid structure has a certain protective effect on the anti-reflection micro-nano structure.Through simulation and experiment demonstration,the composite grid surface can enhance the mechanical stability of the micro-nano structure surface and extend its service life without affecting the optical performance of the micro-nano structure surface.These research results will broaden the use environment and conditions of optical micro-nano structure surface,and help promote the application of optical micro-nano structure surface in the field of high-precision optical detection.