Liquid lens with tunable focus


A lens is an optical device which is used to transmit and refract light. A simple lens has two surfaces, one or both of which are curved. There are two main types of lenses: concave and convex. Concave lenses will diverge light, and convex lenses will converge light. If a parallel beam of light passes through a convex lens, it will be focused at a spot behind the lens. The distance from the focal spot to the lens is called the focal length. If the lens material and both curvatures of the lens surfaces are known, the focal length can be calculated.

smart contact lens

Figure 1. Zoom mechanical lens and smart contact lens

A lens is usually made of glass or transparent plastic and has fixed focal length. Optical systems often require variable focal length to have zoom capability and change the image size. Typical optical zoom system includes a group of lenses and a focusing mechanism with moving parts, such as gears and motors. A tunable lens without mechanical moving parts can significantly reduce the size and complexity of optical system.

Project Description

The challenge of this project is to design and build a lens with a wide tunable focal length. This can be done by sealing liquid in a lens chamber with a deformable elastic membrane. The curvature of the membrane can be changed by pumping liquid in and out of the lens chamber.

principle of tunable lens

Figure 2. Operational principle of tunable lens

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