Fabrication and testing of micro-lens arrays by all-liquid techniques

Various all-liquid fabrication strategies to construct polymer micro-lens arrays on glass substrates are presented. Wettability patterns were made on glass substrates and a monomer was deposited selectively on circular domains on the substrate by making use of the hydrophobic effect, resulting in liquid micro-lenses. The liquid micro-lenses were solidified by polymerization. Three different variations of the selective wetting process were developed. The polymer micro-lenses were characterized extensively by optical methods: focal length, surface roughness and optical aberrations of the lenses were determined by scanning white light interferometry. Due to their fabrication from the liquid phase, the root-mean-square surface roughness of the micro-lenses is between 10 and 35 nm, i.e. better than 1/10 wavelength. These measurements allowed comparison of the quality of lenses fabricated by these techniques.