Fluid focus lensppt

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Fluid focus lens

INTRODUCTION : 

INTRODUCTION

FOCUSSING METHODS CAMERA EYE : 

FOCUSSING METHODS CAMERA EYE

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Conventional camera: Length between lens and focal plane adjusted to focus image. Human Eye: Shape and curvature of the lens changed to focus image

FOCAL LENS : 

FOCAL LENS

FIXED FOCAL LENS : 

A photographic lens for which the focus is not adjustable is called a fixed-focus lens. The focus is set at the time of manufacture, and remains fixed. A Fixed-focus lens relies on sufficient depth of field to produce acceptably sharp images. Fixed-focus cameras with extended depth of field (EDOF) sometimes are known as full focus cameras. FIXED FOCAL LENS

ADVANTAGES : 

It can be produced very inexpensively, more so than autofocus or manual focus systems. The system is also effectively automatic; the photographer need not worry about focusing. It can also be more predictable than automatic systems. ADVANTAGES

DISADVANTAGES : 

The inability to produce images as sharp as a lens that has been set to the best focal point for a given scene. Fixed-focus lenses are unable to produce sharp close-ups, or images of objects close to the camera, usually within 2.4 - 3.7 meters (8–12 feet). The latter limitation makes them unsuitable for portraits, as they cannot fill the frame of an image with a person's face. DISADVANTAGES

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The disadvantage is the reduction of light that will reach the film through the small aperture. Therefore the lenses are usually not suitable for fast-moving objects which require short exposure times .

VARIABLE FOCUS LENS : 

A method of determining the correct focusing distance and setting the lens to that focal point. Produced images are sharp as the lens has been set to the best focal point for a given scene. These lenses are able to produce sharp close-ups, or images of objects close to the camera VARIABLE FOCUS LENS

LIMITATION : 

It requires electronics, moving parts, and power. These lenses require input from the operator. LIMITATION

LIQUID FOCUS LENS : 

LIQUID FOCUS LENS

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It varies its focus by changing shape rather than by changing the relative positions of multiple lenses, as high-quality camera lenses do. It overcomes the fixed-focus disadvantages of many of today’s low-cost imaging systems. The tests of a prototype Fluid Focus lens showed that it can be made nearly as small as a fixed-focus lens.

What are liquid lenses : 

What are liquid lenses Lens formed by meniscus of liquid. Shape of the meniscus is manipulated by some external force.

Typical Application : 

Short tube with transparent ends. Two immiscible fluids Different refractive indices One electrically conducting aqueous and one non-conducting oil Hydrophobic layer on one surface Typical Application

Basic Design : 

Basic Design

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(a) Schematic cross section of a liquid-based variable lens in a cylindrical glass housing. (b) When a voltage is applied, charges accumulate in the wall electrode and opposite charges collect near the solid/liquid interface in the conducting liquid. (c)–(e) Video frames of a 6-mm-diameter lens taken at voltages of ,0, 100, and 120 V.

Electrowetting : 

Electric field changes contact angle effectively changing the power. Electrowetting

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It can be defined as "the change in solid-electrolyte contact angle due to an applied potential difference between the solid and the electrolyte". The fringing field at the corners of the electrolyte droplet tend to pull the droplet down onto the electrode, lowering the macroscopic contact angle and increasing the droplet contact area.

Formation of fluid lens on lens chip : 

Formation of fluid lens on lens chip

Liquid Lens and AssembledCamera Module : 

Liquid Lens and AssembledCamera Module

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It shows a schematic cross section of the module and photographs of the entire camera and electro wetting lens. The height of the lens stack is 5.5 mm measured from the image sensor. The electro wetting cell is positioned between two plastic injection molded lenses.

VGA CMOS Camera having LiquidLens : 

VGA CMOS Camera having LiquidLens

Varioptic Zoom Lens : 

Varioptic Zoom Lens

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Varioptic’s liquid lenses act similarly to the human eye, in that they can change shape, to zoom or focus automatically, without mechanical aid. These combine multiple liquid lenses, with a driver, sensor and image processor to address magnification, change focus and control aberrations.

Design considerations : 

Stability Density Interfacing Design considerations

Typical Performance : 

Typical Performance

FluidLens Features : 

Low cost optical focusing system No moving parts Compact in size Excellent transparency Concave and convex lens formed from single lens Zoom lens created by adding to fixed lens FluidLens Features

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Not prone to scratches Low power usage for automatic focus (1mW ) and no power for manual focus Fast response time (ms)

Applications : 

Telecommunications: Optical switches, fibre optic coupling, mobile phone cameras, webcams Data storage: CD, DVD, barcode readers Analytical equipment: Portable Applications

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microscopes, Sensors Manufacturing: Laser technology Medicine: Endoscopes

Advantages : 

Advantages No mechanical moving parts Inexpensive Small size Fast response

Uses : 

Auto focus camera lens -Cell phone cameras –Security cameras –Webcams and other integrated cameras Uses

Other uses : 

Optical recording Illumination optics Other uses

Liquid camera : 

Liquid camera

CONCLUSION : 

The camera lens uses most of the power of the camera. But now-a-days we want to save power as much as possible. So, here liquid lens shows its ability. It needs very less power as compared to the typical motor driven lens. So, it may be the best alternative of typical motor driven lens. CONCLUSION

References : 

S. Kuipera, B.H.W. Hendriks a, et al “Variable-focus liquid lens for portable applications” SPIE Vol. 5523 pp. 100-109, Oct 2004 Benno H.W. Hendriks, Stein Kuiper, et al "Variable liquid lenses for electronic products" SPIE Vol. 6034 Jan 2006 Jerome Crassous and Claude Garay "Liquid lens based on electro wetting: a new adaptive component for imaging applications in consumer electronics" SPIE Vol 5639 pp. 143-148, Dec 2004 www.varioptic.com References

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Questions?