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Quantum Film Might Replace CMOS Sensors
An anonymous reader writes "Quantum film could replace conventional CMOS image sensors in digital cameras and are four times more sensitive than photographic film. The film, which uses embedded quantum dots instead of silver grains like photographic film, can image scenes at higher pixel resolutions. While the technology has potential for use in mobile phones, conventional digital cameras would also gain much higher resolution sensors by using quantum film material." The original (note: obnoxious interstitial ad) article at EE Times adds slightly more detail.
There seems to be a sensationalist mix-up with the two terms... is this technology going to bring about more sensitive pixels (i.e. higher ISO capabilities) or just more pixels on the sensor? or both?
Can the speed be adjusted like ISO 100-400 etc?
Right now night vision goggles give a very grainy tinged image. Clarifying that could have millions of applications.
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I want the pixels that I have on iso 50 and with F1 over a 700mm objective please. Make it smaller and less 'noticeable' then the L-glass I have to carry with me these days and I might buy myself a new body and some glass... Oh, this one is really important. Make it cheaper please. I know you know that we (photographers) will just give you all that we have for a decent setup, but it would be so cool if a real good objective, would cost less than a real good car.
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With silicon, having to pass through narrow gaps should reduce the amount of light coming at the sensor from an unexpected angle as would occur due to lens flare, imperfections in the lens, etc. Without that, I'd expect the clarity of the image to be impacted. Am I missing something, or is this just trading one problem for another?
Also, how does this improve over already commercially available newer CMOS designs that push the photo-sensitive material to the front surface?
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You can't know if a film is Lawrence Of Arabia or a Rob Schneider picture until you actually watch it. Very spooky at any distance.
how is this different from a Charge-coupled device?
I don't know too much about the physics of photography, but it seems to me that the real problem in the picture quality of tiny cameras is that the lenses are terrible. Improving the sensors just means that we'll get very accurate digital representations of blurry images, produced by tiny, dirty lenses with minuscule, fixed focal lengths. Even as things stand now, a older camera with good optics and a 5MP sensor produces much better images than a new camera with cheap optics and a 12MP sensor. It seems to me that sensor isn't the bottleneck anymore.
I've been waiting for technology that would make my computer's bootup sequence more sensitive to my needs.
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I read a story about this in a recent issue of The Economist. The article focuses more on the other direction -- how quantum dots can be used to enhance LEDs to create more pleasing/efficient/versatile lighting. But it also mentions how they can be used to read light, too; for example, to make better solar panels.
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If this technology could be used to make larger sensors more affordable, that would be quite exciting for the professional and pro-sumer photographers out there. Right now the largest sensors that are in an affordable price range for normal humans are the full-frame 35mm style, and even those are pretty pricey. When you get into the medium format backs, one can expect to spend a similar amount to a new sedan... or in some cases, a new sportscar. As far as I know, they haven't even built a sensor that's large enough to be called "Large format" that's marketable- all the large format digital backs are scanners, as far as I know.
Larger sensors do more than reduce noise and increase low-light sensitivity- they also reduce depth of field, which is something that often separates the amateur photos from the ones taken by the pros. Of course, a cheaper sensor isn't going to reduce the cost of the glass, but maybe somebody else can figure that one out!
According to the articles, both.
In particular:
- It replaces the in-chip photodetector with an on-top-of-chip detector, allowing all the real estate on the chip be used for the REST of the system rather than reserving most of it for light sensors. That means you can use bigger features (and cheaper processes) - and/or get more pixels by shrinking the features back down a bit.
- It gives about a 4x sensitivity improvement. (2x because the quantum dots are more sensitive, another 2x because they get to be on top (so the light isn't attenuated by chip structures) and cover the whole pixel rather than part of it.) You can use that to make 4x more sensitive pixels of the same size, 4 times more pixels of the same sensitivity, or some other tradeoff.
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I dunno about quantum photography, it's neither here nor there.
It gripped her hand gently. 'Regret is for humans,' it said.
Having fixed focal lengths is not bad! Prime lenses always give a quality advantage over zoom lenses, which is why in film production, prime lenses are used almost exclusively when image quality matters. Zoom lenses are only used on budget productions, or when there's actually a zoom in the take.
The issue is that todays sensors reveal lens flaws that could not be noticed with earlier film cameras or older DSLR's. From what I understand it would be very difficult to mass produce cameras and lenses reliably with more resolution. This is why so many lenses are considered defective out of the box. LensRentals.com has a story about it. http://www.lensrentals.com/news/2010.03.06/this-lens-is-soft-and-other-facts
He means fixed focus lenses.
Where do I get my Quantum film developed at ?
I thought photography was getting away from film . . .
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If the sensor gets small enough, the lens can be something other that a refractive solid. Perhaps a drop of liquid in some sort of electrostatic suspension, where problems with the material are far less, and the lens can be focused by reshaping rather than moving.
The lenses are actually getting pretty good. For example, take a look at 300mm f/2.8L. The thing is crazy sharp. Heck, it's still pretty sharp with 2x teleconverter (300mm f/2.8 -> 600mm f/5.6) on it! Or 85mm f/1.2L, wow! Those things could probably outresolve 100MP+ 35mm DSLR sensor.
If anything, it's diffraction that bites you in the ass. Small aperture, like f/22, is just a blurry mess because of it, no matter how good the lense.
Odd, I get crisper pictures with smaller apertures, all else being equal, and I'm pretty sure everybody else in the world does, too. You've got it completely backwards there.
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As an engineer who does astronomical optics rather than a photographer, I can say with certainty with absolute certainty that all else being equal (i.e. diffraction limited case) a larger aperture is sharper. This is simply a matter of physics. The resolution is inversely proportional to diameter of the aperture due to the wave-like nature of light.
Now, if by 'crisper' you don't mean sharper, but rather a fuzzy measure of how you think it looks, its not surprising because smaller lenses of good quality are easier to make, and will thus approach the ideal diffraction limit. But this isn't a case of all other things being equal, and won't be as capable.
To paraphrase Nyeerrmm for laymen, stopping down the aperture, AKA higher f-stop gives you more Depth of Focus or Depth of Field. This means the plane of focus is deeper. Put most simply, the higher f-stop gives you MORE things in focus. So you think it's sharper. But it doesn't mean the things that are in focus are any sharper. More things are sharp, but any one spot is less sharp.
Is this Quantum or Nano technology? Reading the article its sounding more like nano than quantum as field states and other quantum theories are not applied, its simply "really small dots embedded in a substrate" to create a new semiconductor. Its very irritating having people throw quantum around for really small things when nano is more applicable.
That's the trouble with it - you can know its sensitivity or its resolution, but not both, and the act of measuring one changes the other.
... it's vaporware.
Odd, I get crisper pictures with smaller apertures, all else being equal, and I'm pretty sure everybody else in the world does, too. You've got it completely backwards there.
Most lenses reach ideal sharpness around F8, so you are both right.
Smaller apertures and you run into diffraction limitations. Larger apertures and you run into narrow depth of field issues, as well as design issues. I believe it is difficult to accurately manufacture the lens to align at large apertures.
or it didn't happen. Right? Amiright? I slay me. Seriously, though, the article was just a bunch of words. Pretty pictures, that's what I want.
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http://www.scientificamerican.com/article.cfm?id=quantum-dots-cell-camera
"Our quantum film even looks like photographic film—an opaque black material that we deposit right on the top layer of our image chip."
This is important. Current digital sensors are reflective & that results in a specular reflection. This greatly increases the flare, since much of the light the strikes the sensor reflect back into the lens, where it can reflect from a lens back to the sensor. This is one area where digital has been noticeably worse that film. See PhotoTechEDU Day 4: Contrast, MTF, Flare, and Noise @ http://www.youtube.com/watch?v=tNvFsOvVkOg&feature=channel. This is the major loss of contrast at low spacial frequency (eg ~ 10 lp/mm). The digital censors are not living up to the potential of the glass. This could really help. Now if I can just save up enough for a next generation Leica M10...
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Yeah, that's what I was thinking of. You're right. My brain was spacing out. Mea culpa.
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Just to clarify, I wasn't referring to the lens diameter. I'm well aware that you get a more focused image with larger optics. I was referring to the diameter of the iris, and was confusing the depth of field with the focus.
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The Canon 85mm f/1.2 is also a legend. And only about 2 grand.
If these lenses are only 'pretty good', you must be accustomed to the optics in research telescopes ;-)
Think global, act loco
I don't know too much about the physics of photography, but it seems to me that the real problem in the picture quality of tiny cameras is that the lenses are terrible.
It seems to anybody who knows anything about the problem with digital cameras that you don't have a clue. And this statement proves it:
Even as things stand now, a older camera with good optics and a 5MP sensor produces much better images than a new camera with cheap optics and a 12MP sensor. It seems to me that sensor isn't the bottleneck anymore.
The reason the old 5mp camera produces a better picture than the 12mp camera is not because of the optics, it's because of the size of the individual pixels on the chip. The 5mp camera has sensors that are 2-3 times larger than the 12mp camera, which means they can collect that much more light, and therefore can have shorter exposure times and/or more accurate color.
That's why the $1000 + 12mp cameras use an image sensor that is many times the size of a $100 12mp camera - so they can pick up more light. The optics can't improve the picture the image sensor picks up, they can only avoid harming it. That's why they are so expensive, because meticulous care goes into ensuring the lenses don't ruin the picture the image sensor picks up while enabling you to zoom great distances.
What this quantum film is supposed to do is improve the light sensitivity without increasing the size of the image sensor, or allow you to shrink the image sensor without losing light sensitivity. Applying this to camera-phones would allow them to come somewhere in-between current consumer grade cameras and professional cameras, consumer grade cameras would be in the realm of the professional grade sans-optics, and they'd be able to crank up the resolution on professional cameras without losing any quality.
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i think he must mean a deeper "Depth of Field" with a smaller aperature si "sharper". maybe he's not so good at focusing....
-s
You say you want more portable glass. However, you're still asking for a 700mm lens. You do realise, that in order to have 700mm lens at f/1, you need an entrance pupil with 700/1 = 700mm worth of diameter? Yup, that's right, 70cm of diameter in order to achieve f/1. Not sure that's ever going to be portable, mate.
To quote Frank Abagnale Jr., "I concur."
From wikipedia: (http://en.wikipedia.org/wiki/Baker-Nunn_camera#Baker-Nunn)
A dozen f/0.75 Baker-Nunn cameras with 20-inch apertures – each weighing 3.5 tons including a multiple axis mount allowing it to follow satellites in the sky – were used by the Smithsonian Astrophysical Observatory to track artificial satellites from the late 1950s to mid 1970s.
20 in *25 mm/inch = 500 mm. => 500 mm /0.75 = 667 mm Objective, which is pretty close to 700mm. At 3.5 tons, this is only semi-portable.
Think global, act loco
Objective is a perfectly accurate term for the primary lens or mirror in a telescope. A simple telescope is just an objective (mirror or lens) and an eyepiece.
Think global, act loco
A CMOS sensor is smooth and fairly reflective, so it reflects a considerable fraction of the light. This reflected light does indeed cause flare. The second article states that the new sensors are black, so this new sensor could dramatically reduce flare.
Think global, act loco
In order to understand how these dots are optically active, you do indeed need quantum mechanics.
To me, 'nano' is just a word for the boundary between the quantum world and the classical world.
Think global, act loco
Would you have moded up or down? Or is that to be decided by the state of the cat?
Think global, act loco
There are SLR zooms that are amazing optically, easily the equal of a prime. In no particular order:
Olympus 14-35 f/2
Olympus 30-100 f/2
Olympus 90-250 f/2.8
Olympus 11-22 f/2.8-3.5
Olympus 50-200 f/2.8-3.5
Nikon 200-400 f/4
Sigma 300-800 f/5.6 (what a huge thing)
Most SLR lenses aren't diffraction-limited, though. If you go to slrgear.com or dpreview.com and look at performance vs. aperture, you'll notice poorer performance wide open (because of aberrations) and poorer performance closed past f/8 (on Four Thirds) or f/16 (on 35mm format) because of aberrations. Most lenses are best somewhere between f/4 and f/8.
85/1.2L is actually pretty soft around the edges, from what I've heard.
But, yes, long tele primes are excellent, as are some midrange macro lenses (Sigma 150/2.8, Olympus 50/2, etc.)
It's f/5.6 nowadays. I mean, that's the aperture I tend to get sharpest photos on my Canon 5D mark II. Diffraction is already blurring the center a bit at f/8. Of course, more of the remaining frame is sharp, so it's not just bad. I just prefer to have my centers in focus above over the edges.
It's always been a rule of thumb called the "Three Stop Rule" If you stop your lens down by three stops from wide open, you'll generally experience the highest degree of sharpness that the lens has to offer.
Image quality is limited by several factors. The sensitivity of the detector is only one, and is the only one that quantum dots can address. In this instance, the sensitivity increases only by a moderate amount, so the improvement in signal level (or reduction in pixel size preserving signal level) is also moderate.
Increasing the signal level will improve the S/N ratio for readout noise, assuming the readout is comparable to that available in today's cameras. Readout noise has been aggressively tacked by camera manufacturers, and is already very low. The principal source of noise in conventional images is shot noise (photon noise), and this is unrelated to the detector sensitivity. Shot noise depends ONLY on the number of photons arriving at each pixel, and is the reason that darker areas of digital images tend to be noisier, or require information-destroying denoising operations in postprocessing. Other forms of noise, such as dark current and dark noise, are relevant only in special applications, such as astrophotography.
Shot noise is intrinsic in the statistics of photon fluxes. The number of photons arriving at a pixel from a radiance which is "uniform" in time and space is Poissonian: the standard deviation is the square root of the mean. The signal to noise ratio is the mean divided by its square root, which is the square root of the number of photons which arrived in that sampling interval (exposure). If 10,000 photons are expected to arrive at a pixel in a given exposure time, then the shot noise will be about 1% when comparing multiple "identical" exposures of that pixel. Changing the detector sensitivity raises or lowers the readout signal level, but does not change the signal to noise ratio in the signal from shot noise.
Reducing the shot noise requires more photons arriving at each pixel. Getting more photons per pixel requires either (i) bigger pixels on the detector, (ii) better illumination of the subject, or (iii) better optics. This is why professional cameras have larger pixels than prosumer cameras, which tend to have larger pixels than pocket cameras, phone cameras, etc. Better lenses also help (but large apertures also affect depth of field). For given lighting conditions and optics, bigger pixels result in lower image noise, unless the readout circuitry really sucks.
So, quantum dots will result in a higher signal level than conventional CCD/CMOS/CID detectors under similar imaging circumstances. The improvement is probably limited to improving the ratio of signal to readout noise, which is already pretty good. Quantum dots will not magically increase the number of photons arriving at the detector, and if used to reduce pixel size, will result in worse signal to noise ratio for the shot noise (biggest noise problem in most photography). Result: not a dramatic improvement, although detectors giving horribly noisy images (needing heavy destructive denoising) may get even smaller.
Just send the bums some money, so they'll shut up. The potential of quantum dots in imaging sensors has been known for years.
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You don't see any market for smaller cameras?
It's not about smaller cameras - when your pixels are smaller than individual photos (as is the case now), making them smaller only increases the "noise" part of the s/n ratio.
Pixels smaller than photos? Thank god, otherwise we couldn't recognize any details in them.
This is about the laws of physics. I'm sure somebody will correct me if I'm not explaining this very well, but...
There's a limit to how precisely a lens can focus light. Now, in theory, as the aperture gets smaller, the diffusion decreases, so you might think that the small lenses would be result in a more precise image than larger ones. However, with those smaller lenses come smaller image sensors, which means that even if the lens can focus light to a smaller point, the pixels are also smaller, thus canceling out much of this improvement.
The bigger problem is that the smaller the lens, the greater the impact of even tiny lens aberrations on the resolving power of the lens. A speck of dust on a 1.5mm lens makes a huge difference, whereas it can be largely ignored on a lens with a 72mm diameter.
Also, as resolution increases, light gathering decreases. That's pretty fundamental to the laws of physics.
Why don't we just ditch all the optics and its problems and go for "fly eye" type of cameras? We have processing power on modern cameras, we have very dense photo detectors, we could compute the image instead of projecting it in its visible form on the surface of detectors. IMHO, that last part is relict of the past, dragged over all the way back from camera obscura and its limitations are clearly holding us back. Isn't it obvious that, when you map a set of photons that hit one surface onto array of detectors of a different surface, you'll either have information loss or information "invention"(noise)? Why don't we intercept photons right on the outer surface of objective lens? Did you notice how the empty space inside camera is essential for its operation? It is because refraction is based on geometry and geometry needs space. Without that whole ... box thing ... we could have flat, thin, cameras that could fit into our wallets.
..than photographic film!? Sorry, very bad joke. That means they are a factor of maybe 10 less sensitive than CMOS cameras, is it?
I don't think they will capture much more than quantum noise :-(
With a smaller aperture you get a larger depth of field, meaning that a larger distance range appears sharp in the image. If your photos are of a scene with certain depth this might be the reason. But also if your focus wasn't set to th right range a smaller aperture would increase sharpness.
If you make a large format camera smaller, is it still a large format camera? Hmm.
Right now you can get digital backs for large format camerers The Phase 1 P45 is a 39 Megapixel 16 bit, 6x9 frame.
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Actually the result you see is most likely due to the Bayer interpolation which has to "invent" the remaining colors for each sensel. Well not invent, it infers it from the surrounding sensels but still there is a loss of resolution. This always results in an image that is not as sharp as can be at that resolution. Even a "high-end" SLR will be affected by this but will look a lot cleaner due to less quantum noise.
For small digicams there are a couple more factors, noise reduction obliterates detail and quantum noise affects the cleanliness of the image.
Finally in small digicams you may hit the diffraction limit much earlier than their smallest aperture f/8. In the 14Mp Canon G10 I think it happens around f/5.6 or so. It isn't really a lens problem but a sensor problem (pixels too tiny!), but the practical result of it is that you start to lose sharpness.
It depends on the lens. My 300mm f/5.6 would be at f/16 three stops down, well after the point where diffraction eats your lunch on Four Thirds. Same with my 9mm f/4; there's noticeable degradation by f/11. This is because these are slow lenses.
Some relatively fast lenses are so sharp wide open that there's not much improvement from stopping down. Olympus 150/2, 35-100/2, 50/2, Sigma 150/2.8, etc. (I know Four Thirds lenses; I'm sure there are Nikon ones too, etc.)
But the "three stop rule" is true for old standard lenses, especially when used on large formats (fullframe/film) where diffraction isn't as big of an issue, but edge softness is. Your rule is true for my OM 50/1.8; it's best around f/5.6.
Quantum Leap movie?
what?
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This material has a tunable band-gap by using different combinations and ratios of S, Pb, Cu, Ti, Cd, Hg, Te, Ag, etc. Silicon sensors and their exotic equivalents have fixed, and very limited band-gaps. Additionally silicon based sensors have a rather limited quantum efficiency which is about 40% to 50% efficient under idea configurations. CMOS imagers are anything but idea configurations.
OmniVision's innovation of using BSI didn't increase their efficiency to 80%, it reduced the number of photons absorbed by interfering metalization. area over front-side illuminated solutions... under ideal conditions. This is where the 40% - 50% efficiency numbers come from, and they cannot say so with a straight face because the trenching around the sensor's pixels reduced the coverage over the array... increasing the gaps between pixels.
With this new material they get increased conversion efficiency from the material and increased active area within the pixel with the first-surface configuration. (the metal area is hidden under the photo-sensitve layer, with no trenching. With the tunable band-gap they also get to target IR solutions with sensitivity to wave lengths >1000nm. Si can't do that at all. With other tunings they get improved visible light sensitivity.
While the material is far more toxic than silicon-only solutions, it is a lot cheaper to deposit. Don't eat the film and you should be fine :)