Showing papers by "Hao Bian published in 2022"

Bioinspired Anti‐Fogging and Anti‐Fouling Artificial Compound Eyes

Abstract: Curved artificial compound eyes (ACEs) attract enormous research interest owing to their potential applications in medical devices, surveillance imaging, target tracking, and so on. However, fog, dust, or other liquids are likely to condense on the device surface under a humid, low‐temperature environment or outdoors, thus affecting the optical performance. In this work, a multi‐functional ACE (MF‐ACE) is fabricated by a combination of i) femtosecond laser wet etching, ii) soft lithography, and iii) polydimethylsiloxane (PDMS) swelling methods. The fabricated device is close‐packed with over 3000 microlenses (≈108 µm diameter and ≈15 µm height) on a spherical macrolens (6.56 cm diameter and 0.87 cm height). The trapped silicone oil in the cross‐linked PDMS endows the as‐fabricated ACE with excellent water repellence and anti‐fogging, anti‐fouling, and self‐cleaning abilities. In addition, the ACE shows high optical performance and the ommatidia have a spatial resolution of 50.8 lp mm−1. The imaging and focusing experiments demonstrate its high optical properties and uniformity. It is anticipated that this research may provide useful guidelines for the fabrication of anti‐fogging and anti‐fouling optical devices, and such device enables potential applications in autonomous vehicles, medical, or vision systems under harsh environmental conditions.

Microlens arrays enable variable-focus imaging

Abstract: Microlens array (MLA) is a key part of optical element for biomedical inspection, lab-on-a-chip device, and light-field cameras. However, conventional MLAs always have only one focal plane, which makes them difficult to capture targets at different positions. To solve this problem, a planar multi-focus MLA (MF-MLA) was prepared on a polydimethylsiloxane (PDMS) substrate by a combination of femtosecond laser wet etching (FLWE) and soft lithography techniques. The modulation transfer function (MTF) values of the microlenses all exceeded 0.2 when the spatial frequency was less than 200 lp/mm, indicating the high imaging ability of the lenses. The reported MF-MLA had three different focal lengths, so that targets at different positions could be easily imaged on a single image sensor. In addition, MLAs with more focal points could be fabricated by selecting appropriate processing parameters. It is anticipated that the as-fabricated MF-MLA will become a promising device to improve the performance of the optical system, especially in optical remote sensing, biomedical imaging, and machine vision.