Fluidic lenses with variable focal length

Abstract

We demonstrate in this letter that variable focus lenses can be realized by pressure-induced deformation of a liquid interface. Large deflections can be achieved by exploiting the capillary pressure barrier generated by high surface tension liquids at the exit of a small well. Modulation of the internal pressure of a liquid interface produces a change in its radius of curvature thus a shift in the plane of focus. Using liquids with high surface tension like water and polymeric low surface energy substrates, liquid-air lenses were realized with a wide focal length tunability (optical power for 2 mm lenses from 130 to 350 diopters). Using the liquid-liquid interface of water and a nonmiscible liquid, pressure-induced tunable lenses were also demonstrated. The application of the lenses in imaging was also shown.

High speed adaptive liquid microlens array

“…Various concepts of adaptive lenses have been developed in recent years to match the increasing demand for a variety of applications including mobile phones, surgical endoscopes, security cameras and DVD players [7]. Next to liquid crystal-based approaches novel liquid lenses in various configurations have been proposed using responsive hydrogels [3], piezoelectricity [8], acoustics [4] and Electrowetting (EW) [9][10][11][12][13][14] as actuation mechanisms. The latter is particularly useful for the design of compact and robust devices combining simple electrical driving with actuation speeds exceeding video rate for sub-millimetric lenses.…”

Adaptive Liquid Lens Actuated by Droplet Movement

“…Since the response time depends on the LC layer thickness and the size of the LC lens, it is more suitable for making microlens which constrains the real applications in imaging systems. There are three common operating mechanisms to design a liquid lens: electrowetting effect [6][7][8][9][10][11][12][13][14], dielectric force [15][16][17][18], and fluidic pressure [19][20][21][22][23][24].…”

“…According to the difference of the filled materials, it can be roughly classified into two categories: liquid crystal (LC) lens [1][2][3][4][5] and liquid lens [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. An adaptive LC lens usually employs an OPEN ACCESS inhomogeneous electric field to make the LC molecules reorient to produce a gradient refractive index profile.…”

Effect of the Liquid Density Difference on Interface Shape of Double-Liquid Lens

“…Currently in most of the studies about the double-liquid lens, the two liquids' densities are the same to ensure that the liquid interface is a spherical surface [8,9]. The density difference of two liquids can affect the interface shape and the final focal length of the system [10].…”