Antireflective coatings on Fresnel lenses by spin-coating of solid silica nanoparticles

Antireflective (AR) coatings were fabricated from solid silica nanoparticles (SNPs) of ca. 16 nm in size on Fresnel lenses via one-step spin coating without any high temperature treatment. Transmission electron microscopy was used to observe the morphology and structure of the SNPs. Transmission spectra were recorded on a UV-vis-NIR spectrophotometer. The results indicated that Fresnel lenses covered with the SNPs coatings were much more transparent than the uncoated Fresnel lens. The maximum transmittance of the coated Fresnel lenses reached as high as 99.8%, whereas that of the uncoated Fresnel lens is only 94.3%. Surface wettability was studied by a contact angle/interface system, and the results indicated that the coatings on Fresnel lenses were more hydrophilic than the uncoated Fresnel lens. The surface morphologies and structures of the coatings were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The mechanical robustness of the coatings was examined by pencil scratch tests and attenuated total reflection infrared spectroscopy (ATR-IR).