Acta Optica Sinica, Volume. 45, Issue 10, 1022002(2025)
Design and Analysis of Cylindrical Liquid Lens Based on Electrowetting
Cylindrical lenses, with their unique ability to focus light in a single dimension, are critical for applications such as beam shaping and improving illumination uniformity. However, most existing research on electrowetting-based liquid lenses focuses on spherical configurations, leaving cylindrical variants underexplored. These cylindrical lenses face challenges such as high driving voltages, limited focal ranges, and structural inefficiencies. In this paper, we address these challenges by proposing a novel cylindrical electrowetting liquid lens design featuring a conical cavity with segmented dielectric layers. Our approach aims to advance cylindrical liquid lens technology for compact optical systems, targeting low-voltage operation (35?55 V), wide focal length tunability (139?999 mm), and enhanced optical performance. We provide foundational insights for applications in laser processing, optical sensing, and medical imaging by bridging theoretical advancements with practical implementation.
We employ a multidisciplinary approach combining theoretical analysis, numerical simulations, and experimental validation. The lens structure incorporates a conical cavity with alternating thick (15 μm) and thin (3 μm) dielectric layers [Fig. 1(d)], enabling asymmetric liquid interface control based on the Young-Lippmann equation (Eq. 1). Theoretical modeling establishes the relationship between applied voltage and interface curvature, while a fifth-degree polynomial (Eq. 2) ensures high-precision fitting of simulated interface profiles (R2>0.98, Table 1). COMSOL Multiphysics 6.0 simulates voltage-dependent interface deformations (Fig. 2), and Zemax evaluates optical performance, including focal length, aberrations, and field curvature (Figs. 6 and 7). Fabrication involves photolithography and parylene-C deposition to create dielectric layers (Fig. 8), followed by experimental testing using a laser-CCD setup to measure focal length indirectly via spot width analysis (Figs. 10 and 11).
The gradient in the dielectric layer of the conical cavity enables precise control of the liquid-liquid interface. Upon voltage application, the thin dielectric regions exhibit reduced contact angles, driving the interface displacement, while the thicker regions remain static [Figs. 1(b) and (c)], forming a cylindrical surface in the central region (Fig. 4). COMSOL simulations confirm focal length modulation from 998.67 mm (35 V) to 139.01 mm (55 V) (Table 2), which is consistent with theoretical predictions (Eq. 4). Zemax analysis shows minimal aberrations and field curvature at 5° field angles (Fig. 7), with focused light in the Y-Z plane and negligible focusing in the X-Z plane at 55 V [Figs. 9(e) and 9(j)]. Experimental spot widths (Table 4) closely match simulations (e.g., 0.49 mm experimentally vs. 0.46 mm in simulation at 55 V) (Fig. 12). Compared to previous works, this lens operates within a 35?55 V range, significantly lower than existing designs, and offers a wide focal length range (139?999 mm) than existing cylindrical lenses. The conical cavity design minimizes edge effects and eliminates mechanical components, enhancing the lens’s structural robustness [Fig. 1(d) and Fig. 4].
In this paper, we present a novel electrowetting cylindrical liquid lens that delivers superior performance. Key innovations include a conical cavity structure that enables low-voltage (35?55 V) focal tuning over a wide range (139?999 mm), overcoming prior limitations of high voltage and narrow tunability. Integrated simulations (COMSOL, Zemax) and experimental validation confirm the lens’s cylindrical focusing behavior, minimal aberrations, and practical feasibility. This lens has significant potential for beam shaping and illumination uniformity enhancement, offering a compact and mechanically stable solution for applications in laser processing, optical sensing, and medical imaging. Critical theoretical and experimental foundations are provided, bridging academic research with industrial implementation and paving the way for future advancements in miniaturization, response time optimization, and multifunctional optical system integration.
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Le Zhou, Xiangteng Ma, Wenfeng Zhao, Xifeng Li. Design and Analysis of Cylindrical Liquid Lens Based on Electrowetting[J]. Acta Optica Sinica, 2025, 45(10): 1022002
Category: Optical Design and Fabrication
Received: Feb. 24, 2025
Accepted: Apr. 2, 2025
Published Online: May. 19, 2025
The Author Email: Xifeng Li (lixifeng@shu.edu.cn)
CSTR:32393.14.AOS250629