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Ultraviolet Digital Cameras
An anonymous reader wrote in to tell us that "Scientists at North Carolina State University's Solid State Physics Laboratory say they have built a
camera that can take pictures of anything that emits ultraviolet light." And we'd like to announce an update to the RobCam: I think Hemos and I will be wearing a lot more white.
We must protect our children!!!!!! Oh, wait.....I thought you said UltraVIOLENT digital cameras.....
No, near UV light has been imaged since the early days of film photography. But I believe this is a significant advance in the direct electronic detection of UV light. As someone else said, UV light is usually detected electronically by fluorescence: take one UV photon, and use an absorptive chemical film to convert that into two visible light photons. (That's what Tide laundry soap does to make "whites whiter!" etc.)
The energies discussed are definitely "near-UV". That is, wavelengths of 200-400 nanometers (the human eye can see from about 400 (blue) to 700 (red) nm. Far UV (about 100 nm) and Extreme UV (less than 100 nm) are not included in this technology. X-rays (1 nm and shorter) are definitely out (but actually, CCDs are used on the new Chandra X-Ray satellite in funky ways). Down to about 100 nm (or maybe lower?) you can use conventional lenses, but they must be made out of magnesium-fluoride (MgF) instead of glass. It's not really until X-rays that you have to use bizarre techniques to focus light (like nested grazing-incidence foil mirrors).
This is new technology to do a better job of old science (at least from the astronomical point of view).
It would be very interesting if they can get aluminum gallium nitride diodes to emit coherent uv radiation, talk about data storage on CD's... Anyone know of other UV laser technologies? I know that there hasn't been any success in creating an X-ray laser yet; X-ray emissions, yes, coherent, no (last I heard).
...disciplining the ronkeys since 3/2000...
1024 detectors could produce a high resolution image if they were layed out along one axis and the source image was scanned across the other axis using a fast detector sample rate.
This must have been the method used with the early imaging satellites back in the sixties. There is no way they could have fit enough photomultiplying tubes into a small satellite with only solar power.
This is an interesting development, and it is likely that this technology has significantly higher efficiency than using CCDs, and so will become useful in astronomy when they can make arrays of a few hundred pixels square. The article however greatly oversells the significance of this.
I saw it too. Stories have popped in and out of existence on slashdot before. Let's not assume the worst. Remember, Rob can't even spell beta :-)
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Fuck the system? Nah, you might catch something.
Where I work we have digital cameras* that take pictures in 3D and work with gamma rays. And a camera that constructs 3d images from radiowaves in a magnetic field.
PET and MRI (aka NMR) are old technology tho, PET's resolution being limited to ~8mm iirc, due to the fact that a positron has to drift a certain distance before annihilating (Statistically speaking). MRI's drawbacks are that you cant have any metal in the subject.
Oh, and they're both expensive
(* If you define a digital camera as something that creates images from life)
-Yarn - Rio Karma: Excellent
"All stars emit ultraviolet light, so compact digital cameras sensitive to that wavelength could open a new window on the universe."
Erm, yeah, like I didn't know that?
More to the point, what is a digital camera, at eg 1152x864 resolution, going to see that the big boys can't now?
I think the whole thing is just a tad simplistic but ludicrously optimistic, typical journalist-meets-brains syndrome...
~Tim
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Rushing on down to the circle of the turn
Indeed, I noticed it too. Strange.
...they're also sensitive to IR - try aiming your TV remote at one. Lots of fun can be had confusing people by making displays out of IR LEDs so that they can only be seen on a monitor! (incidently, anyone ever tried saturating their car/bike number plate with IR to defeat speed cameras? ;)
[Happosai]
To follow up my claims, here is the URL.
I do not know how long it will last...
(But it is working right now!)
Most people keep UV filters on their lenses to protect their expensive glass from dust and scratches. However, I've shot hundreds of rolls of film, 35mm and medium format, and have never noticed uv fogging. The amount of uv light reflected by everyday objects is very small compared to visible and infrared (unless taking pictures directly into the sun).
We can't handle the truth? WTF?
hmm, maybe that explains why some posts obviously intended for that article are appearing here.
-Yarn - Rio Karma: Excellent
That's why they're usually said to cut the "haze" on overcast and hazy days -- the lower light levels makes it more noticable. Its also a matter of what colors the light registers as on the film as compared to the visible-light color of the same object. Sometimes it'll just minutely shift the color and fuzz the outlines. How stopped down the lens is, what kind of lens it is and factors like that also affect it. You'll almost never notice it on a handheld shot. But if you shoot a scene on a more overcast day on a tripod with and without the filter, depending on the camera it can be very noticable.
The more glass there is in the lens (the more elements) you also strip out more and more UV.
Do some searching on the net, I've seen a half-dozen sites with ultraviolet galleries.
Most standard chemical-based film stock is also ultraviolet sensitive. That's why even novice photographers know to put a UV filter on the lens, because lenses focus the ultraviolet at a different point than the other colors (and ditto with infared, although non-infared film is rarely very sensitive to infared, whereas most film is fairly sensitive to ultraviolet), and you get a hazy look to the film -- the haze is just a blurry exposure of the scene in ultraviolet.
For any amateur shutterbugs out there, if you can find a quartz lens that fits on your camera (they're very hard to find and VERY expensive unless you get really lucky), you can get filters to put on the lens that will cut out all the visible light, letting the ultraviolet through, and you can actually shoot very interesting photos in UV using standard film. Exposure times are longer, and you've got to guess on the exposure because meters won't read the light levels, however.
WTF? Now that you are an IPO you can only post "P-C" storys?!?
I have to return some videotapes...
Is this supposed to be the first time anyone has detected UV light? Anything that emmitts UV huh? What about energies so high they are almost X-Rays? At those frequencies the index of refraction of all materials are almost the same. How would you even build a lens for the thing? Pin hole camera? We don't know what frequency they are talking about, and we don't know how this is really different from what people have done in the past. Basically this tells me nothing.
The device itself has a LONG way to go before being useful for a lot of applications that need more than a simple 'detection' of UV. The article says that the chip is an array of 1024 detectors (ie: a 32x32 array) which is hardly enough for any serious visualization usage. It is a good first step on the way to 'consumer grade' UV detectors which are good enough to be considered cameras.
Right now, it's just a small slab of detectors a few dozen on a side. While even at that size it could be very useful in certain applications (I've got my doubts about the weld examination if one only has a 32x32 pixel window to view with!) it won't be really widespread-useable until there's at least a 256x256 (or maybe 300x200, given digital's trend towards 3x2 ratios) pixel device. Then I expect you'll have spy shops all across the net selling UV-enhanced spy cameras. ;)
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rickf@transpect.SPAM-B-GONE.net (remove the SPAM-B-GONE bit)
"People will pay big bucks for the luxury of ignorance."
Yes, what did happen to it....sounds fishy....
I can see it now. Hidden web cams at popular make out spots with ultraviolet flashes. I would like to see one of these on a hand-cam, or in an infered version.
-- Virtual Windows Project
What *I* found interesting in this article was the mention that the same types of diodes could be used to generate many different wavelengths of light very efficiently, and that they were being used for such purposes in Japan as billboards already.
Does anybody have any guesses/info about how what kind of resolution (both spatial & for color) you can generate using these types of diodes, and for how much?
Like the sony nightvision cams w/ filters???
Otherwise, geeze, what's the point.
:-)
Poor Rob, it was a tough decision.
So can a $30 refurb Connectix B/W Quickcam, if you
do a little surgery on it.
As far as my experience goes, photodiodes and photodiode arrays have been used extensively for spectroscopic applicaitions such as UV absorption, fluorescence, etc., for quite some time. If you have around $20k, you can call HP and get a nice UV-VIS adsorption spectormeter with photodiode array detector for your very own :)
There may indeed be a breakthrough in design which may reduce costs, increase efficiency, wavelength rage, etc., or possibly a novel use for UV detection/sensing. But this article does not point anything like that out. This defiantely does not seem like a fundamental scientific breakthrough.
I really like if thats kirlian cameras become cheaper...
Currently the majority of visible and near-visible astronomy is done with CCD cameras (same technology as typical digital cameras and camcorders) which have peak sensitivity in the red or even IR. This makes it rather hard to study blue stars. The further blue you go, the less transmissive the atmosphere is and the brighter scattered moonlight appears (y'know, the sky is blue and all). So, having a camera that has poor sensitivity in the blue is doubly bad.
On a less technological and more historical note, prior to the 1980s (or so), photographic film was the dominant technology for astronomical imaging. Since most film has higher sensitivity in the *blue*, there was a lot of astronomy done at that end of the spectrum. Using CCDs today, it can be hard to compare to the blue work of the past. With new cameras specializing on blue and UV light, better comparisons with previous work can be made.
So it's quite wrong to say that new UV cameras will open up a new window in astronomy. In fact they will reopen an old window!
Even the CCD on my Sony handicam can see IR... just switch on the 'night shot' mode (which basically introduces a IR filter into the optics and kicks on a small IR spotlight on the front, IIRC) and away I go. It'd be nice to have similar sensitivity in the UV spectrum, for "cool toy" purposes if nothing else. ;)
Thing is, UV light has a tendancy to make things floresce (glow), so useful applications for clandestine surveilance would probably be limited to available-light... ie: have no real advantage whatsoever.
(I'm not going mention that someone setting up spycams at 'make-out spots' really needs to find a new hobby or three...)
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rickf@transpect.SPAM-B-GONE.net (remove the SPAM-B-GONE bit)
"People will pay big bucks for the luxury of ignorance."
http://www.discovery.com/cams/sun/sun.ht ml
Although they admit that it's actually four separate cameras, each just capturing one wavelength of UV light - so presumably using different technology?
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