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Graphene-Based Image Sensor To Enhance Low-Light Photography
cylonlover writes "A team of scientists at Nanyang Technological University (NTU) in Singapore has developed a new image sensor from graphene that promises to improve the quality of images captured in low light conditions. In tests, it has proved to be 1,000 times more sensitive to light than existing complementary metal-oxide-semiconductor (CMOS) or charge-coupled device (CCD) camera sensors in addition to operating at much lower voltages, consequently using 10 times less energy."
There was this article on slashdot 4 years ago, http://science.slashdot.org/story/09/07/23/1819215/people-emit-visible-light.
Summary:
"The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal. Japanese researchers have shown that the body emits visible light, 1,000 times less intense than the levels to which our naked eyes are sensitive. In fact, virtually all living creatures emit very weak light, which is thought to be a byproduct of biochemical reactions involving free radicals."
So humans emit light that is 1,000 times too weak to detect, but this new sensor is 1,000 more sensitive to light, what a coincident! I imagine this would have great applications in the health industry eg. passive health assessment. Or another use might be a better lie detector :)
Is there any readily available consumer products, or even industrial products, that use graphene? If not then how long do we have to keep hearing about how great graphene is before we can actually use it?
They claim 1000 times better sensitivity than CMOS, which people seem to be swallowing hook line
and sinker, however since there are plenty of current CMOS sensors with a Quantum Sensitiviy (QE)
of 60% to 80% for visible light, how exactly will the convert 1000 times more efficiently than that?
1000 times less loss would take them from 80% to 99.99%, that thats only actually 20% better...
I would imagine they are measuring at an extreme wavelength that existing CMOS sensors do not target,
hardly an advantage for the applications being discussed in the article (normal cameras).
Even quite boring consumer cameras have a QE of 20% to 40%..
As I recall, quantum efficiency of current sensors is around 50%. I don't see how you can get "1000 time more sensitive".
news from Singapore under China section? ..
Here's the actual paper. It's paywalled though...http://www.nature.com/ncomms/journal/v4/n5/full/ncomms2830.html
According to the paper, "Through this scheme, we have demonstrated a high photoresponsivity of 8.61A/W, which are about three orders of magnitude higher than those in previous reports from pure monolayer graphene photodetectors.". So it is 1000x better than previous iterations of a particular variety of detector, not the detectors we actually use.
How do you get a decent image if you have to peer through the sticky tape used to grab the graphene?
Graphene, is there anything it can't do?
Amateur photographer here. Does this mean that the camera will just be able to photograph at higher ISOs without noise (or rather, that you could use a lower ISO in darker situations), or that the sensor will be able to record a picture with a wider stop range? Digital cameras have a range of about 6-7 stops, whereas our eyes have a 16-stop range (according to Bryan Peterson). HDR can be used to remedy this, but, more often than not, the pictures seem much too blown, saturated and unnatural. Sony has an in-camera HDR function, that can be tweaked to keep the color explosion at bay, but it is not exactly it. Being able to take photos in bad light is sweet and all, but it would be much more interesting creatively to have a camera that can picture what I see, without having to set up a whole flash array for lighting up all the dark areas (and having to imagine and troubleshoot, if I have the time, the combination of a flash+natural light exposure).
So photo-gurus, will this sensor cut it? Are there any products in the market that address the issue described above?
Since contemporary CCDs can be single-photon sensitive with 0.7 quantum efficiency, I doubt it's 1000x better. But nevertheless...!
Next thing you know, there's going to be announcement that the kitchen sink is going to be made out of graphene.
"The only normal people are the ones you don't know very well."
Stop figuring out more cool stuff graphene can do. We get it. You scientists are smart. You can make wiz-bang things none of us will ever own!!!
Why do I say we will never own them??? Because you spend all your time figuring out new ways to use awesome materials and no fucking time on ways to make it commercially producible without using shit loads of tape. We need 4'x8' graphene sheets for $100 or less each at Lowes before you figure out another way graphene can make X product Y% more seXY.
Here's the actual Nature Communications article, not a mangling by some incompetent tech journalist.
What can this do to help us extend the length of fiber optics, or lower the transmitter power on long runs like overseas?
now we need to go OSS in diesel cars
Aren't we talking about the Kirlian effect? that's been known for many and I mean, may years. Some people whom believe in psychics would say it is our Aura. Anyways, it's nice to see that the realm of the metaphysics is about to cross in the "explained" phenomena and hopefully with some actual science to explain what we are really made of.
Yes. You're a twat.
systemd is Roko's Basilisk.
Yes, you are absolutely right - QE is already high even in "boring" cameras. It is also true that the readout noise of the modern boring sensors used in cellphone cameras is also of the order of a single electron (each photoelectron counts), so you can not significantly increase low-light sensitivity for the same pixel size and same exposure time. You can make large pixel (or use "binning" of the smaller ones) - and it is well known part of the existent technology. Other parameter important for the low-light imaging is dark current - this is why many astronomical CCDs are cooled and exposed for hours - just to be able to increase exposure. Exposure is not "exponential", in is not less linear than QE, so if you increase exposure 1000 times you'll be able to detect 1000 dimmer light source, But for video that is irrelevant - boring sensors already have negligible dark current for video, so this (the only way to increase "sensitivity" for the same pixel size) is only applicable to long exposure scientific applications.
There are some sentences in the article that indicate that they mean exactly that - using longer exposure:
And of course, talking about "5 times less expensive" without having a viable technology of integrating graphene with CMOS - what the crap is it? You know why silicon-based CCD technology is dying now? Just because you can not combine CCD (light capturing array) and CMOS (phase drivers, ADC, memory, CPU if you font SoC) on the same silicon chip - I do not see how carbon graphene is more compatible with CMOS.
CCDs already have a quantum efficiency of 10-50% depending on wave length. This thing is 1000X more efficient? How does that work?
They invented street gangs. But seriously, they love their mothers.
1) The article speaks about a thousand fold improvement in sensitivity when compared to present CCD and CMOS image sensors. In reality in the actual scientific publication it is said that there is a 1000 fold improvement in photoresponsivity when compared to other mono-layered grapheen sensors - there is no comparison to present image sensors.
2) Photoresponsivity depends on two factors Quantum Efficiency (QE) and amplification. The QE of a grapheen mono-layer is 3% meaning that the new grapheen sensor must be an amplified sensor (it cannot have a QE of 3000%). Most likely there is no improvement in QE at all in which case the present CCD and CMOS image sensors beat the mono-layered grapheen sensor by 20 to 30 times in QE for visible light which is the only part of the spectrum used in photography.
3) Amplification is not desired in photography since it introduces amplification noise which reduces the image quality. Besides in silicon sensors you can also introduce amplification if it is desired (see e.g. Electron Multiplication CCD, EMCCD, Intensified CCD, ICCD, Single Photon Avalanche photo-Diode SPAD) and in addition you can easily amplify the charge 1000 fold or even much more.
4) The figure of merit in image sensors is not photoresponsivity but Signal to Noise Ratio (SNR) which takes into account the signal and all the related noise sources. The signal depends on the photon flux, pixel size, QE, amplification (if used), and integration time. The different noise sources are photon shot noise, dark noise, read noise, and amplification noise (if amplification is used). Only the SNR tells you how sensitive the sensor is, that is, how faint signals the sensor can detect.
6) The grapheen based sensor of the article does not integrate charge unlike the CCD and CMOS image sensors meaning that in a pixel matrix (i.e. image sensor) the integration time of individual grapheen pixels would be very limited and thus such a grapheen matrix sensor could be used in bright light only. For low light you would need to have integrating pixels which could be realized with pixel specific capacitors.
7) The benefit of having a response for a broad spectral range from visible light to infrared radiation (beyond 10 um) is beneficial e.g. in spectroscopy. However, the ability to detect infrared radiation means that the sensor has a very high dark noise level unless extensively cooled. According to the publication it seems that at least in some experiments they have kept the device at 12 K which is very, very cold and unsuitable for photography.
8) Since the sensor is extensively cooled the overall power consumption would be also much higher than in CCD or CMOS image sensors.
9) According to the publication the time it takes to adapt to different photon flux levels takes really long time - in the order of tens of seconds which is naturally prohibitively long for photography or video imaging.
10) In the publication a value for read noise is not disclosed. The read noise is most likely much higher than in integrating CCD and CMOS image sensors utilizing Correlated Double Sampling (CDS) readout which is the key for low read noise. So far nobody has even presented how to realize CDS readout in grapheen sensors.
10 times less than what? Unless you're already comparing two things, then that's not really a useful measurement.
Now if you said, A uses 120W, B uses 110W, but C uses 10x less, one could assume that C uses around 20W.
Assume we only know about A and C, we could say that C uses about only 17% the energy of A.