Fabrication and investigation of the bionic curved visual microlens array films

• Published in: Optical materials Vol. 66; pp. 630 - 639
• Main Authors: Kuo, Wen-Kai, Lin, Syuan-You, Hsu, Sheng-Wei, Yu, Hsin Her
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2017
• Subjects: Curved microlens array; Field of view (FOV); Langmuir-Blodgett (LB); Monolayer; Ommatidia; Monolayer; Ommatidia; Langmuir-Blodgett (LB); Field of view (FOV); Curved microlens array
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2017.03.020

The compound eyes of insects are smaller, lighter, and have a wider field of view and high sensitivity to moving targets. In recent years, these advantages have attracted many researchers to develop minimized optical devices. In this study, a high performance microlens was fabricated, mimicking the biological visual feature. Polystyrene (PS) microspheres were synthesized by dispersion polymerization first, and then a close-packed monolayer of PS microspheres was assembled by the Langmuir–Blodgett (LB) deposition method. Following this, a 2D polydimethylsiloxane (PDMS) concave mold was fabricated by a soft lithography technique. Different aperture sizes of poly(methyl methacrylate) (PMMA) curved microlens array replicated films were prepared using traditional Chinese medicine cupping tool with a temperature-controllable hot plate, which eliminated the need for inconvenient metal modeling. The optical performance of the curved microlens films were evaluated by a system of optical microscopy (OM) and a home-made image capture charge-coupled device (CCD). The field of view (FOV) and the light intensity distribution of the curved microlens array were also investigated. We found that a broader field of view corresponded to a smaller aperture size of the curved microlens films, as the convex heights of the films are identical. The resolution of the curved microlens films was not affected by their aperture sizes, but was determined by their interommatidial angle and the diameter of the microlens. [Display omitted] •An ordered monolayer of PS microspheres was assembled by the LB technology.•Curved microlens array films were prepared using a Chinese medicine cupping tool.•Lenses with smaller aperture sizes shown broader fields of view at the same height.•The resolution of a curved microlens was determined by the interommatidial angle.