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An Origami Lens for Your Camera Phone?
Roland Piquepaille writes "Your next camera phone might get a new kind of lens if researchers at the University of California at San Diego convince the cell phones makers. They have designed an 'origami lens' which will slim high resolution cameras. Today, their 5-millimeter thick, 8-fold imager delivers images comparable in quality with photos taken with a compact camera lens with a 38 millimeter focal length. In a few years, these bendable lenses could be used in high resolution miniature cameras for unmanned surveillance aircraft, cell phones and infrared night vision applications."
It's a reflector. Don't ask me how it works, the story and illustrations aren't very clear. But it's not a lens, fresnel or otherwise.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Despite what the summary says, the "lense" isn't bendable. It just manages to compress a lot of light-bending capability into a small space by using reflective, rather than refractive optics and combining all the optics in a single crystal. I say "lense" because it's not refractive, so it's not really a lense.
pi = 3.141592653589793helpimtrappedinauniversefactory7
This looks pretty cool, but...
I see two disadvantages, and both of them relate to the fact that the light-gathering surface is now a donut.
The first is that the light-gathering ability is greatly reduced when compared so something else with the same width lens. On the plus side, if you are "shortening" your lens, you probably do not mind "fattening it up" in order to compensate. This also means that the lens cover on your cell phone cam will be bigger, so you have a larger area to get scratched, a larger area to wipe fingerprints off of before shooting, etc. No big whoop, but something to be aware of.
The second is that blurry objects tend to blur in the shape of the aperature. The classic picture of this is taking a picture of your sweetie standing in front of a Christmas tree covered with white lights. With a conventional lens, if the Christmas lights are blurry, they will tend to be little fuzzy circles. With the new lens, they will be little glowing fuzzy donuts. So this is probably not what you want for portrait work.
Still pretty cool, though. It will be interesting to see how this develops.
"-1 Troll" is the apparently the same as "-1 I disagree with you."
And don't get me started on the quality of the Britney/Paris upskirt pics....
ACK NAK RST
This is actually nothing like a Fresnel lens. Fresnel lenses are based on refraction and tend to give horrible image quality since they have a whole bunch of concentric rings. This lens does things a completely different way. It's really a pretty clever piece of optics. It's functionally equivalent to putting a conical reflector over the imaging device and another reflector at the edge or the lens. They just get a longer focal length by bouncing it up and down more.
ACK NAK RST
This is actually nothing like a Fresnel lens. Fresnel lenses are based on refraction and tend to give horrible image quality since they have a whole bunch of concentric rings.
You misspelled "burn the shit out of stuff"
The theory of relativity doesn't work right in Arkansas.
Something else to think about... cost of manufacture. If this is designed for small form factor it is most likely going into consumer electronics. If you are dropping several hundred bucks on a digital SLR you don't mind a big lens. Cost becomes an issue with $100 mass produced Taiwanese gadgets. This seems like it will cost a helluva lot more than a simple plastic standard lens. That only leaves a small market for expensive cameras with form factor restrictions. Or so it seems.
Silulu. Hot Polynesian Geek Chick.
I want a telephoto adapter for my cell phone camera so I can use my cell phone as a tele-phone.
I'm not sure if I want something like this if it means it comes in at f11 or the like. Who wants a cameraphone that you can only use on sunny days, has a flash range that's measured in nanometers or comes with an ISO rating that requires scientific notation?
*IF* this can turn in f stops close to or equal to prime focus lenses or good quality zooms, for a reasonable price, then I'm interested. All those 75-300mm f5.6-f8 (or worse) lenses are useless, IMO, even with today's faster ISO chips/films. Gimme my old 180mm f2.8 any day.
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
I see two disadvantages, and both of them relate to the fact that the light-gathering surface is now a donut.
Donuts... Is there anything they can't do?
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Here is one of many greasemonkey script to remove piquepaille stories
http://userscripts.org/scripts/show/5735/ [userscripts.org]
don't cut it off www.mgmbill.org
They are only going to use the Diamond cutter to produce the master for the molded glass lenses. After the master is created cost of molding a plastic reflective imager is pretty much the same as cost of molding a plastic lens. They do need more software but we all know software is free as in beer Right?
**Life is too short to be serious**
This lens has the same problem as any lens-system with a central obstruction; the contrast for medium-scale detail is poor, due to diffraction effects.
Image quality is generally specified using a concept called Modulation Transfer Function (MTF). It is like a frequency response for lenses except the frequency is spatial in cycles per mm rather than Hertz.
Lenses with a central obstruction can have comparable MTF with respect to unobstructed lenses of the same speed, at spatial frequencies near the limit of resolution. However, you try very hard not to use a lens that way because the performance is poor. At the more important, intermediate spatial frequencies, an unobstructed lens has much better performance.
Astronomers have picked up on this idea. They like to use reflective lenses with a central obstruction for viewing stars where resolution limit is the only thing that counts and the perfect colour correction provides an advantage. However, unobstructed refractors are better for planets where you have a distributed image.
It is possible to make reflective telescopes without a central obstruction but the technology is still a little expensive. I expect, one day, they will displace refractors.
Aliasing is another issue using a centrally-obstructed lens with a pixellated image sensor like a CCD or CMOS device. Spatial frequencies above the Nyquist limit (2 pixels per cycle) generate garbage within the pass-band of the detector. A lens of this type concentrates its performance in the worst frequency range for the detector.
There are lots of promising approaches for cheap, compact lenses for cell-phone cameras but I doubt this lens is one of them.
This lens has exactly a second mirror blocking the center of the main lens itself.
Did you not look at the diagram? The thing blocking the aperture is the second mirror.
The "zone reflectors" are the 1st, 3rd, 5th, etc. mirrors.