Soheila Hesaraki

Out Line

Types of liquid lensHistory of liquid lens used Electro

wetting effectThe basic idea (Electro wetting

mechanism)ComponentsAdvantages and drawbacksApplicationReferences

Types Of Liquid Lens

Fluid membrane interaction

Dielectrophoretic effect

Thermal effect

Electro wetting effect

History

17th

century

•Stephen Gray, an English scientist made microscopes by creating water-drop lenses. He kept the drops from moving around by placing them in holes drilled in a plate

1936

•Froumkine, experimenting with the use of electric fields to change the shape of a water drop sitting on a metal surface

1995

•Gorman and his colleagues at Harvard University made the first variable-focus lens, by replacing the metal plate with a transparent conducting plate

2000

• • Bruno Berge and Jerome Peseux improved on Gorman's design by covering the transparent electrode with an insulating film, and adding the means for centering the drop

Electro Wetting

With the applied potential, the contact angle of the conductive liquid was changed, which was referenced as electro wetting.

Electro Wetting

Electro Wetting

Liquid Lens structureThe lens has a simple structure: two liquids,of equal density, sandwiched between two windows in a conical vessel

Traditional way to perform the Auto Focus functionMechanism : Moving mechanically the

lensmodule to adjust the focal lengthDrawbacks:- Necessity of bulky and fragile motors- Friction of small parts leading to

damage and malfunction after a few hundreds of thousands of actuations

- Noise and high power consumption while moving the mass of the lens module

Advantages1. No moving parts

2. High Speed : 2/100th of a second

3. Low power consumption: <1 mW (~15 mW with driver)

4. Silence

5. High shock resistance : thanks to the simple mechanical structure and iso-density

6. A large focal length range

Advantages

7. Small size (Up to 85% smaller than standard camera lenses) Useful in applications which need size and weight savings like mobile phones

8. It has got a wide operating temperature range i.e. -50°c to 180°c

9. The cost of manufacturing is very less.10. The curvature and the focal length of

the liquid lens can be switched from concave to convex.

Drawbacks1. it should not be subjected to

temperature beyond the specified range or else water will freeze inside it and this may damage our system. It can be improved by adding antifreeze like ethylene glycol

2. Size limitation(gravity effect and aberration problem

caused by a non-uniform lens Shape)

Application

-Barcode readers- Medical imaging- Endoscopes- webcams- Ophthalmology equipment- hidden security cameras- DVD recorders- Zoom Lens- - Tumor detection

Future Applications- A key component of a future implantable

artificial eye

Thanks for your attention !

References1. “ Jihwan Park,” A Liquid Lens Based On Electro

Wetting”, Louisiana State University. Masters Thesis, August 2007

2. http://www.varioptic.com

3. “ SCOBIE, FRASER,CHARLES,” Adaptive Optical Devises in Vision Science”, Department of Physics University of Durham. PHD Thesis, September 2012

4. Liquid Optics Product catalog

5. “B. Berge,” Liquid Lens Technology: Principle Of Electro Wetting Based Lenses And Applications To Imaging,” IEEE Transactions, 2005

6. http://www.nature.com/naturephotonics