A high numerical aperture, polymer-based, planar microlens array

Abstract

We present a novel microfabrication approach for obtaining arrays of planar, polymer-based microlenses of high numerical aperture. The proposed microlenses arrays consist of deformable, elastomeric membranes that are supported by polymer-filled microchambers. Each membrane/microchamber assembly is converted into a solid microlens when the supporting UV-curable polymer is pressurized and cured. By modifying the microlens diameter (40-60 microm) and curing pressure (7.5-30 psi), we demonstrated that it is possible to fabricate microlenses with a wide range of effective focal lengths (100-400 microm) and numerical apertures (0.05-0.3). We obtained a maximum numerical aperture of 0.3 and transverse resolution of 2.8 microm for 60 microm diameter microlenses cured at 30 psi. These values were found to be in agreement with values obtained from opto-mechanical simulations. We envision the use of these high numerical microlenses arrays in optical applications where light collection efficiency is important.

Enhanced Self‐Organized Dewetting of Ultrathin Polymer Films Under Water‐Organic Solutions: Fabrication of Sub‐micrometer Spherical Lens Arrays

“…These micro-lenses are shown to provide lens based near-fi eld focusing in high resolution optical microscopy. [ 6 ] In biological systems there are several examples of array of miniaturized lenses such as insect's compound eyes. [ 7 ] Micro-lenses are used in a variety of optical devices like charge-coupled device (CCD), digital projectors and photovoltaics.…”

High numerical aperture microlens arrays of close packing

“…However, technical realization of such MLAs remains challenging despite massive efforts 5-10 toward high fill factor 5-7 and high NA. 8,9 For example, the highest NA achieved from 100% fill factor MLAs produced by thermal reflow, 5,7 multistep UV lithography, 6 Ni-Co electroplating and hot embossing is solely 0.13; while the fill factor from high NA MLAs prepared by microfluidic technology 8 and digital projection photopolymerization 9 is lower than 50%.…”

A doublet microlens array for imaging micron-sized objects

“…EFL values of 65–75 μ m were obtained for glass microspheres ranging 57–63 μ m in diameter. Experimental EFL values were obtained for individual microlenses in the array using collimated white light (see [25] for details on the experimental setup used to measure the EFL). The EFL measurement process involved obtaining the best focused plane by capturing a stack of images along the microlens axis and finding the plane with the maximum light intensity.…”