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Microlens array is a fundamental optical components that are widely used in the various applications including 3D display, light homogenization and 3D imaging. Lots of advanced fabrication techniques have been demonstrated for producing microlens arrays with different geometries, profile and optical properties. However, microlens arrays with high filling factor whose microlenses are closely packed are hard to realize due to the difficulty in 3D micromanufacturing techniques. In this research, a novel rapid and low-cost microfluidic-manipulation based technique is proposed for fabricating high-filling-factor microlens array. An array of micro-holes are firstly prepared as mold on a silicon wafer by lithography technique. Then, polydimethylsiloxane (PDMS) is used to replicate the micro-hole array to form the micro-post array. After that, liquid-state PDMS is spun over the micro-post array and solidified. Due to the existence of the micro-posts, PDMS presents wavy fashion. The PDMS right on the top of the micro-posts becomes spherical cap while those in between the micro-posts becomes valley due to the capillary effect. The microlenses are closely attached to each other and the entire mircrolens array is highly packed. In this paper, we present a preliminary demonstration about the fabrication. A microlens array is formed on a 500 μm in diameter micro-post array. The closely packed microlens array patterned in square style achieves the filling factor above 78.54%. The geometry and profiles of the microlenses could be designed and controlled. The easy-to-operate fabrication technique is suitable for mass production of microlens arrays.
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