We present design and fabrication of a multi-focusing microlens array (MLA) using a thermal reflow method. To obtain multi-focusing properties with different numerical apertures at the elemental lens of the MLA, double-cylinder photoresist (PR) structures with different diameters were made within the guiding pattern with both photolithographic and partial developing processes. Due to the base PR layer supporting the thermal reflow process and the guiding structure, the thermally reflowed PR structure had different radii of curvatures with lens shapes that could be precisely modeled by the initial volume of the double-cylinder PR structures. Using the PR template, the hexagonally packed multi-focusing MLA was made via the replica molding method, which showed four different focal lengths of 0.9 mm, 1.1 mm, 1.6 mm, and 2.5 mm, and four different numerical apertures of 0.1799, 0.2783, 0.3973, and 0.4775.
© 2014 Optical Society of Korea
(120.2040) Instrumentation, measurement, and metrology : Displays
(220.4000) Optical design and fabrication : Microstructure fabrication
(230.3120) Optical devices : Integrated optics devices
(130.3990) Integrated optics : Micro-optical devices
Original Manuscript: December 27, 2013
Revised Manuscript: January 7, 2014
Manuscript Accepted: January 7, 2014
Published: February 25, 2014
Min-Kyu Park, Ho Jun Lee, Ji-Sub Park, Mugeon Kim, Jeong Min Bae, Imtiaz Mahmud, and Hak-Rin Kim, "Design and Fabrication of Multi-Focusing Microlens Array with Different Numerical Apertures by using Thermal Reflow Method," J. Opt. Soc. Korea 18, 71-77 (2014)
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