Microlens Arrays Fabricated from All-Liquid Techniques

7 Microlens Arrays Fabricated from All-Liquid Techniques 

Moench etal. explored three different liquid fabrication strategies to construct polymer microlens arrays on glass substrates [14]. First the glass substrates 

Change in focal length and numerical aperture for different post heat treatments. The heat treatment temperatures were 91,120, and 190°C (aU above the Tg of PS of 90°C) generated on a hot plate for 5 min. = focal length. = numerical aperture. (Source Huang, J.Y., Y.S. Lu, and J.A. Yeh. 2006. Optics Express, 14(22), 10779-10784. With permission.) 

All three methods of depositing the liquid monomer involved dewetting. If dewetting occurs under water, the stronger interaction causes the water to repel the monomer from the hydrophilic domains and forces it to remain on the hydrophobic domains. This is the underlying principle for the repelling method [14] and the dipping method [13]. 

The two approaches are in fact quite similar. The difference is that in the repelling method, water is added to the monomer solution for the dewetting process, and in the dipping method, the sample with applied undiluted monomer is dipped into a water reservoir accurate control of the dipping speed is achieved through a motorized stage. If the monomer film dewets in air, the monomer remains on the hydrophilic domains of the substrate. This is the case with the withdrawal method [15,16] in which the patterned substrate is completely immersed in the monomer and pulled out at a fixed angle and a controlled speed into ambient air. 

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