Strain-tunable optical microlens arrays with deformable wrinkles for spatially coordinated image projection on a security substrate

In Sik Choi; Seongho Park; Sangheon Jeon; Young Woo Kwon; Rowoon Park; Robert A Taylor; Kwangseuk Kyhm; Suck Won Hong

doi:10.1038/s41378-022-00399-7

Strain-tunable optical microlens arrays with deformable wrinkles for spatially coordinated image projection on a security substrate

Microsyst Nanoeng. 2022 Sep 14:8:98. doi: 10.1038/s41378-022-00399-7. eCollection 2022.

Authors

In Sik Choi^#¹, Seongho Park^#^{2

3}, Sangheon Jeon^#¹, Young Woo Kwon⁴, Rowoon Park¹, Robert A Taylor³, Kwangseuk Kyhm¹, Suck Won Hong¹

Affiliations

¹ Department of Cogno-Mechatronics Engineering, Department of Optics and Mechatronics Engineering, Pusan National University, Busan, 46241 Republic of Korea.
² Research Center for Dielectric and Advanced Matter Physics, Pusan National University, Busan, 46241 Republic of Korea.
³ Department of Physics, University of Oxford, Oxford, OX1 3PU UK.
⁴ Department of Nano-Fusion Technology, Pusan National University, Busan, 46241 Republic of Korea.

^# Contributed equally.

Abstract

As a new concept in materials design, a variety of strategies have been developed to fabricate optical microlens arrays (MLAs) that enable the miniaturization of optical systems on the micro/nanoscale to improve their characteristic performance with unique optical functionality. In this paper, we introduce a cost-effective and facile fabrication process on a large scale up to ~15 inches via sequential lithographic methods to produce thin and deformable hexagonally arranged MLAs consisting of polydimethylsiloxane (PDMS). Simple employment of oxygen plasma treatment on the prestrained MLAs effectively harnessed the spontaneous formation of highly uniform nanowrinkled structures all over the surface of the elastomeric microlenses. With strain-controlled tunability, unexpected optical diffraction patterns were characterized by the interference combination effect of the microlens and deformable nanowrinkles. Consequently, the hierarchically structured MLAs presented here have the potential to produce desirable spatial arrangements, which may provide easily accessible opportunities to realize microlens-based technology by tunable focal lengths for more advanced micro-optical devices and imaging projection elements on unconventional security substrates.

Keywords: Engineering; Optical materials and structures.