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Philips Develops Fluid Lenses
Lars T. writes "Digital Photography Review has a short report indicating: 'Philips Research at the CeBIT exhibition is demonstrating a unique variable-focus lens system that has no mechanical moving parts. Suited to a wide range of optical imaging applications, including digital cameras.' Here is Philips' press release and the Heise News article (in German) where I first heard about it. The latter also mentions that Philips has recently used the same electrowetting effect in an 'ePaper' display prototype."
"Suited to a wide range of optical imaging applications, including digital cameras." I take this to mean that it is not ready for precision applications and that it may not be. either way, this will take time to get any better
Choosing the lesser of two evils is a choice for evil.
Would it be possible to adapt this type of lens to eyewear by enlarging the size? Instead of using bifocals or trifocals, you might be able to have just one lens that changes shape according to a microcontroller, which is then hooked to either a button, or perhaps tapped into a nerve, which can then be trained to send the appropriate signals.
There was an article in New Scientist a few weeks ago about a lense that changed it's focus in response to an electric current, iirc.
It was made of some plastic and I think the current changed the density of the plastic at some point in the structure in order to change the focus.
Of course, the aim was the same: "Make a lense without moving parts" - these guys must have developed a better solution because the Lense was very poor in the NS article.
Simon.
Look at their demonstration photo and ask yourself. Lens the size of the tip of its developer's finger?
Or developer with a finger...the size of a camera's lens!
You be the judge.
This is the last time I fall for the grotesquely-oversized-finger demonstration trick. Fool me once, shame on you; fool me twice...
Philips' Fluid Lenses
Wednesday, 3 March 2004 21:40 GMT
Philips Research at the CeBIT exhibition is demonstrating a unique variable-focus lens system that has no mechanical moving parts. Suited to a wide range of optical imaging applications, including digital cameras. Philips' FluidFocus system mimics the action of the human eye using a fluid lens that alters its focal length by changing its shape. The new lens, which lends itself to high volume manufacturing, overcomes the fixed-focus disadvantages of many of today's low-cost imaging systems.
Press Release:
Philips' Fluid Lenses Bring Things into Focus
At this year's CeBIT Exhibition in Hannover Germany, Philips Research is demonstrating a unique variable-focus lens system that has no mechanical moving parts. Suited to a wide range of optical imaging applications, including such things as digital cameras, camera phones, endoscopes, home security systems and optical storage drives, Philips' FluidFocus system mimics the action of the human eye using a fluid lens that alters its focal length by changing its shape. The new lens, which lends itself to high volume manufacturing, overcomes the fixed-focus disadvantages of many of today's low-cost imaging systems.
The Philips FluidFocus lens consists of two immiscible (non-mixing) fluids of different refractive index (optical properties), one an electrically conducting aqueous solution and the other an electrically non-conducting oil, contained in a short tube with transparent end caps. The internal surfaces of the tube wall and one of its end caps are coated with a hydrophobic (water-repellent) coating that causes the aqueous solution to form itself into a hemispherical mass at the opposite end of the tube, where it acts as a spherically curved lens.
The shape of the lens is adjusted by applying an electric field across the hydrophobic coating such that it becomes less hydrophobic - a process called 'electrowetting' that results from an electrically induced change in surface-tension. As a result of this change in surface-tension the aqueous solution begins to wet the sidewalls of the tube, altering the radius of curvature of the meniscus between the two fluids and hence the focal length of the lens. By increasing the applied electric field the surface of the initially convex lens can be made completely flat (no lens effect) or even concave. As a result it is possible to implement lenses that transition smoothly from being convergent to divergent and back again.
In the FluidFocus technology demonstrator being exhibited by Philips Research at CeBIT 2004, the fluid lens measures a mere 3 mm in diameter by 2.2 mm in length, making it easy to incorporate into miniature optical pathways. The focal range provided by the demonstrator extends from 5 cm to infinity and it is extremely fast: switching over the full focal range is obtained in less than 10 ms. Controlled by a dc voltage and presenting a capacitive load, the lens consumes virtually zero power, which for battery powered portable applications gives it a real advantage. The durability of the lens is also very high, Philips having already tested the lens with over 1 million focusing operations without loss of optical performance. It also has the potential to be both shock resistant and capable of operating over a wide temperature range, suiting it for mobile applications. Its construction is regarded as compatible with high-volume manufacturing techniques.
(A) Schematic cross section of the FluidFocus lens principle. (B) When a voltage is applied, charges accumulate in the glass wall electrode and opposite charges collect near the solid/liquid interface in the conducting liquid. The resulting electrostatic force lowers the solid/liquid interfacial tension and with that the contact angle q and hence the focal distance of the lens. (C) to (E) Shapes of a 6-mm diameter lens taken at different applied voltages.
Prototype FluidFocus lenses
Photos courtesy of Philips
I dont know about scaling it up. The article is short on details which relate much to eyewear. Eyeglasses correct a huge range of flaws in eyes; by far not the least of which is astigmatism, (wildly popular) which is when your cornea is not curved the same in all axis. (For example, your eyeglasses correction may need to be different vertically than horizontally.)
Astigmatism isn't going to lend well to this, would be my guess, but who knows maybe those wizards can make assymetrical fluid shapes.
Secondly, the size.. why make it big? Make it small like contacts (your eyes dialate only to 5 or 6 mm as an adult.) And put it close. Bizarre tiny eyeglasses is the ticket.
Frank Herbert had a similar idea in Dune: he referred to a pair of binoculars having "oil lenses" that were shaped electrically.
Just another instance of science fiction authors' jobs getting harder, I guess.
I remember that fluid lenses have been used by holographers for a long time, because they can be of quite high quality even with large diameter. Vari*lite also uses fluid lenses in some of their intelligent lighting fixtures.
The News here is that the Philips lens can be focused by an electric field with no part moving other then the lens. The size of their prototype is tiny; IMHO they need at least to triple the size of it to make it useful for digital cameras.
-- www.linux-laser.org - Open Source Laser Show Software for Linux
Could this be a step for manufacturing artificial eyes? Being able to actually zoom in with my eyes would be cool, and if it has NekkidVision(TM), it would be even better :)
Founder of Mirror Moon - Tsukihime Game Trans
A lone researcher did it to make cheap bifocals a few years back. It is an extremely inexpensive way to provide a "one size fits all" pair of glasses for everyone who needs them. No custom lenswork needed - just pump liquid in or out :)
For single lens cameras, no coatings are not that big a problem.
For multiple lens cameras, it can lead to a lot of chromatic aberations.
If these oil lenses can accept liquid optical layers, look out Karl Zeiss.
I guess you where sleeping your way through the optics lectures: These lenses could definitely work. If you look at the picture
you see that there are two fluids: brown one on top and a blue one on the bottom. If you remember Snell's law (ray bends towards the normal in the denser medium), you can conclude from the picture that the 'brown' fluid has a higher refractive index than the 'blue' fluid. The left picture thus resembles a hollow/concave/negative lens and the right picture resembles a convex/positive lens. Of these the positive (on the right) can be used to form a real image (one you can capture on a CCD or a retina), whereas the negative only forms a virtual image.
A colleague of mine did his internship at the group that invented these and my boss still works part-time at Philips.
karma police: arrest this man, he talks in maths; he buzzes like a fridge, he's like a detuned radio. [radiohead]
Everyone keeps saying this. I looked at the diagram, and at least one part of the lens moves. That's a moving part, folks. Stop saying it "has no moving parts".
Now, here are some predictions:
Please help metamoderate.
This is nothing new. Run enough current through a person and you'll see 'electrowetting' in action! 'Electrosoiling', too.
You must think in Russian.
I am a scuba diver and I always wanted to have a small camera when i dive. The ones you can buy now are quite expensive and fragile. Most models use a underwater housing for a standard digital camera that is quite fragile. There is a rubber O-ring around the enclosure to keep the thing water tight. But sometimes you get some dirt on the rubber and the camera leaks when you are 30m below the surface, spoiling your camera.
So I have always dreamt of a hermetically closed camera. You could fill it with a liquid (oil?) to reduce the pressure stress on the enclosing. (This is what current scuba computers do.) By using a digital camera, you don't have to open the camera to access the film. The problem so far has been how to construct a zoom lens since these vary in volume. This kind of lens seems to fix that problem!
)9TSS
How fast can you change focus? If you can change faster than the time it takes to take a picture, you could actually use different focus for the same picture. Each pixel could look on the values of a few neighbour pixels to find out when the picture is sharpest in this region and save only the pixel value from that time. Information about the actual focus used could be saved in the alpha channel. Imagine a picture of an object 10cm from you where both that object and the background is sharp.
Do you care about the security of your wireless mouse?
This is way cool...
This makes a lot of things possible that would have been prohibitively expensive, mechanically improbable, or optically restrictive. A small lense with fast focusing, which is high quality, shock resistent (this would depend on oil viscosity and lenses size), and remarkably cheap to manufacture in large numbers would revolutionize;
* Robotic vision,
* Consumer electronics,
* Security and Research imaging,
* Medical Imaging, and Lense Replacement.
You could cover a robot with cheap eagle-eye imaging devices, create a central imaging system that sews all the images together to produce an ultra-highres 360 degree whole world views. This machine would literally have eyes in the back of it's head. Give the critter broad spectrum vision, and spectrospopic analysis, and this robot could be used for anything from public safety, to mineral evaluation for mining. If you're going to buy a robot, make sure it has "Phillip's whole world vision(tm)".
This makes disposable highres digital cameras and camcorders totally practical. It makes low end devices possible, products for tens of dollars or less, that have the optical features you would expect to find in products that now cost hundreds of dollars. This is especially true if you combine glass element(s) to the lens. You get the power and optical benefit of a glass front lense, a large optical aperture for light gathering, with simple focus and zooming capabilities provided by liquid lenses. A superior lense with a huge list of advantages. Sign me up!
Now that you have a high quality cameras selling for $10.00, you can put them anywhere and everywhere. Imaging for a whole host of purposes becomes ubiquitous (orders of magnitude more prevalent than today.)
Beside giving medical devices better vision, replacing the lense in the human eye, with one that is for all intents and purposes perfect, would be a godsend to millions of people with cataracts, degenerative lense desease, and missing or injured lenses. In the end, this might become so common place, that when you get to that age where folks noadays begin buying multifocal glasses, our descendents will simply get a super lense implant, and have bionic visual abilities that we can only imagine. Would you trade your eyes in for one's that gave you superwide angle and telescopic capabilities? Oh, and for those folks with astigmatic trouble, one could circle the inside of the lense barrel with panels, and apply differing voltages to the panels so as to create a lense shape consistent with any corneal asymetries. This would be the hot new product among the rich and graying!
Genda