Tunable Focus Liquid Microlenses Using Dielectrophoretic Effect

4 Tunable Focus Liquid Microlenses Using Dielectrophoretic Effect 

We previously described an LC droplet-based microlens developed by Cheng et al. [7]. The focal length was tuned using the dielectric force described in Section 5.2.3. Cheng further extended the design and introduced new liquids to a packaged liquid lens actuated by a dielectric force [12]. 

A similar mechanism was utilized to form liquid microlens arrays by Ren s group [13]. To form the liquid microlens array, two immiscible dielectric liquids were used. The first designated L-1 had a relatively low dielectric constant and high refractive index. The second (L-2) had a higher dielectric constant but lower refractive index. 

Side view of droplet array forming processes for liquid microlens array, (a) Two liquid layers. (b) Droplet forming process, (c) Stable state with voltage applied, (d) Relaxed state without voltage applied. (Source Ren, H. and S.T. Wu. 2008. Optics Express, 16(4), 2646-2652. With permission.) 

Focal lengths of dielectric liquid lens versus applied voltages. Triangles and diamonds indicate measurement results and paraxial approximations, respectively. Source Cheng, C.C. and J.A. Yeh. 2007. Optics Express, 15(12), 7140-7145. With permission.) 

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