from the but-don't-look-into-the-light dept.
Night vision goggles do a great job of countering the human eye's poor ability to see in the dark, but the devices are usually bulky, requiring several layers of lenses and plenty of power. But thanks to research from the Australian National University (ANU), a new type of nanocrystal could grant night vision powers to a standard pair of specs, without adding any weight.
Darkness, as we perceive it, is the absence of light on the visible spectrum that our eyes can detect, but there's still plenty of light at other frequencies that we can't use. Night vision goggles make use of the near-infrared spectrum, and convert the photons from that light into electrons that light up a phosphor screen inside the device to create the image. But all that makes for a chunky, power-hungry device.
The ANU team's nanocrystal can be used to create night vision devices that forgo electricity completely, by converting incoming photons from infrared light into other photons on the visible spectrum, to allow the human eye to see in the dark.
(Score: 1, Informative) by Anonymous Coward on Thursday December 08 2016, @10:42AM
http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.6b03525 [acs.org]
Looks like a solid bit of research that has nothing to do with night vision.
(Score: 4, Interesting) by dvader on Thursday December 08 2016, @01:11PM
I haven't read the article but the linked abstract says "transform the frequency" which could mean turning invisible light into visible. The image suggests it is up-conversion, from low frequency to higher (from w to 2w), that is from IR to visible (or at least less IR).
Since higher frequency photons carry more energy than lower frequency, it can't be a one-to-one conversion but must be a conversion of at least two low energy photons to one high energy photon. To get a sharp image, the direction of each photon must be preserved which means the momentum of the first photon must be "stored" in the antenna until the second photon arrives and both can be released. I guess the momentum of the outgoing photon is the sum of the ingoing ones. So the antenna itself must be highly directional so it doesn't absorb light from vastly different directions. I also assume each antenna is tuned to a single frequency as well...
That's enough speculation for now. Maybe someone with a bit more knowledge of optics can explain this in detail.
(Score: 0) by Anonymous Coward on Thursday December 08 2016, @01:34PM
Well, while speculating, it could also be that the first photon is simply absorbed (with no information but its energy remaining, minus the energy cost of the recoil, of course) and the second photon then gets the energy of the first added, without changing its direction (again, with an energy correction due to recoil). Assuming the photons are uncorrelated and sufficiently many, that would still give a pretty good sampling of the original photons, that is, a pretty good image.
(Score: 3, Informative) by dlb on Thursday December 08 2016, @01:57PM
Second harmonic generation (also called frequency doubling or abbreviated SHG) is a nonlinear optical process, in which photons with the same frequency interacting with a nonlinear material are effectively "combined" to generate new photons with twice the energy, and therefore twice the frequency and half the wavelength of the initial photons.
There's some clever things going on here in this field...
(Score: 2) by JeanCroix on Thursday December 08 2016, @09:21PM
(Score: 0) by Anonymous Coward on Thursday December 08 2016, @06:45PM
> To get a sharp image,
A sharp image may not be necessary.
Consider modern digital image compression. It works by breaking out chroma (color) and luma (brightness) and the chroma is half the resolution of the luma. For example a typical 1920x1080 hdtv frame will have 1920x1080 pixels of brightness (8-bit) and 960x540 pixels of each Red/Green/Blue. The human eye integrates the higher resolution brightness with the lower-resolution color to get an image that is perceived to be the full resolution.
So, if these are used in low-light conditions, rather than black-out conditions, we might get the same effect where fuzzy infra-red upconverted photons are integrated with the natural-light photons to produce an image the brain perceives as sharp enough.
(Score: 2) by Webweasel on Thursday December 08 2016, @10:46AM
I wear glasses and I don't need night vision for anything.
What I do need is glasses that work at night while driving, the reflections and glare from headlights and so on make driving really difficult.
I hate driving at night, but I don't have a choice. It is winter and the sun sets at just before 4pm.
Please solve that problem before you solve a problem no one really needs you too.
Priyom.org Number stations, Russian Military radio. "You are a bad, bad man. Do you have any other virtues?"-Runaway1956
(Score: 0) by Anonymous Coward on Thursday December 08 2016, @12:27PM
wear polarizing sun glasses. They cut down reflections to almost nothing.
or get a specialist to stick a sheet of polarizing thingie on your windshield.
something like this:
https://www.amazon.com/Polarizing-Film-Sheet-Gadget-Electronics/dp/B004X3XFHU [amazon.com]
(Score: 2) by Webweasel on Thursday December 08 2016, @02:03PM
Well, sunglasses at night is a no go unless I'm in some bad Canadian band.
And unfortunately you can't have anything on your front windscreen except a sunstrip at the top in the UK, putting a sheet across the whole would be against the law.
Priyom.org Number stations, Russian Military radio. "You are a bad, bad man. Do you have any other virtues?"-Runaway1956
(Score: 0) by Anonymous Coward on Thursday December 08 2016, @02:52PM
you could check if this is legal in the UK:
https://www.amazon.com/Eforstore-Automotive-Sunvisor-Anti-Glare-Driving/dp/B00IM9NLO8/ref=pd_day0_263_5?_encoding=UTF8&psc=1&refRID=P5E36KMB5S7Z1EVAS1PK [amazon.com]
I don't drive, so I've never used one, but for this price I guess it wouldn't be a big deal if it turns out to be useless.
my stepfather bought one at some point, but I never asked if it helped (I live in a different country).
(Score: 3, Informative) by Capt. Obvious on Thursday December 08 2016, @04:47PM
Polarizing glasses work. They shouldn't be sunglasses (it's night), and that will naturally cut about 1/2 the light you see. But it should cut like 90+% of the glare. You make the call for if that is a good tradeoff. But, I tend to think even at 50%, what with headlights and all, you'll still be safer with polarizing glasses. Esp. with the ability to widen your eyes when it's dark.
I don't recall why polarizing filters cut glare, but they work.
A lot of offerings [amazon.com] for such glasses combine it with a yellow filter to try to make the less light you see feel brighter. And, there are perscription options for under $20 [zennioptical.com].
Or even just try attaching a polarizing film to some old glasses (or holding in front of your face.)
Kinda obviously, do all this while a passenger.
(Score: 2) by darnkitten on Thursday December 08 2016, @11:04PM
I just want to be able to see the damned deer.
(Score: -1, Offtopic) by Anonymous Coward on Thursday December 08 2016, @11:48AM
didnt know a predator spaceship crashed in australia??
(Score: 0) by Anonymous Coward on Thursday December 08 2016, @12:51PM
. . . it may not.
(Score: 0) by Anonymous Coward on Thursday December 08 2016, @02:08PM
But unfortunately won't be happening in 20 years atleast. They haven't stopped charging extra for the regular features yet.
(Score: 1) by Francis on Thursday December 08 2016, @09:38PM
Depends where you are. In the US, Luxottica is one of the few sellers of the various components necessary to make glasses. There are other companies, but you have to look for them, because Luxottica has purchased basically all the old companies and offers products under a huge number of different labels. They're the primary reason why frames that cost $10 to make sell for $300 or more.
(Score: 2) by Dunbal on Thursday December 08 2016, @02:20PM
a new type of nanocrystal could grant night vision powers to a standard pair of specs, without adding any weight.
The batteries though...
(Score: 2) by dlb on Thursday December 08 2016, @02:39PM
(Score: 2) by Foobar Bazbot on Thursday December 08 2016, @04:40PM
They're brilliantly using the energy of the photons themselves to power the change in frequency.
Which means no amplification; in fact there's less photons out than in. So it won't let you see by skyglow/starlight/etc. like current NV gear; it'll only be usable with active NIR illumination, which means batteries.
(Score: 2) by takyon on Thursday December 08 2016, @04:56PM
You could use a gene therapy on yourself to make your eyes more sensitive to low light conditions.
kek
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 3, Interesting) by dlb on Thursday December 08 2016, @06:12PM
However as the lead author of the study implied in the article, embedding millions of these nanocrystals inito a thin film on a pair of glasses would open up a wide swath of invisible frequencies, including "near-infrared illumination," to our vision. Think of all the invisible EMR bouncing around out there. If so, then the glasses wouldn't need additional energy.
Either way, wearing a pair of those glasses at night, or even during the day, is going to be an experience I'd love to have.
(Score: 0) by Anonymous Coward on Friday December 09 2016, @03:56AM
Either way, wearing a pair of those glasses at night, or even during the day, is going to be an experience I'd love to have.
Replying back-to-front, I absolutely agree -- the abiity to have full color vision at frequencies one, two, or three (or more? but losses multiply, so I'm afraid not) octaves down from visible wavelength would be fascinating. I'm not sure this is the most practical realization of such IR-seeing goggles, but it's absolutely a cool idea.
embedding millions of these nanocrystals inito a thin film on a pair of glasses would open up a wide swath of invisible frequencies, including "near-infrared illumination," to our vision. Think of all the invisible EMR bouncing around out there. If so, then the glasses wouldn't need additional energy.
But it doesn't open a wide swath -- if you absorb two photons, and reemit one photon with half the wavelength, you're basically just shifting the human eye's 400-750 THz (750-400nm) range down an octave to 200-375 THz (1500-800nm). (While you should be able to stack them in series to go two or three octaves down, it's not clear whether you can do this in a way that, as Immerman suggests, would add all those bands together. For now, let's just consider a single-octave filter.)
We can consider this in two ways -- I find frequency easier for this particular problem, as that graph is better-behaved in the region of interest, but wavelength is more commonly used, and of course they'll both yield the same answer.
The discrepancy, of course, is due to the different types of spectral density -- it's analogous to the difference between a world map using Mercator vs. Gall-Peters projections.
So now all we need is a spectrum of our light source. While we're not likely to use sunlight directly, starlight is basically comparable (despite some stars being redder and some bluer), and moonlight is simply reflected sunlight, so it's a decent first approximation, and it's easy to get data on. Here's a nice page with both graphs shown [sciencequestionswithsurprisinganswers.org] -- though that refers to sunlight in space, or as it enters the atmosphere; I couldn't quickly find a similar pair of graphs with atmospheric absorption included, but NIR is attenuated more than visible. I think you'll agree, using either method with the corresponding graph, that the power in the NIR band is not quite enough to break even. (Though as Immerman points out, if these add to, rather than obscuring, visible light, that may still be helpful.)
Airglow, for what it's worth, is much higher in NIR than visible -- not sure that's enough to make this viable, since it's very dim in the visible, but it's an interesting angle I hadn't considered.
However, if we're talking about stray light generated on or near Earth's surface (e.g. skyglow from a nearby city or highway), we have to consider two types of light. First, we have blackbody radiation -- whether from a fire or an incandescent lamp, this will tend to be comparatively cool, and have less visible light; in fact, these light sources should do much better than break even. On the other hand, we have LEDs, fluorescent lights, discharge lamps of various sorts, etc. -- these all have non-blackbody spectra selected or designed to provide visible light, and thus very likely to have little NIR content. (The rather bright sodium line at 819nm might seem like a counterexample, but of course that ends up at a barely-visible 410nm.) I believe these non-blackbody sources, taken together, already dominate generic city skyglow and lighted highways, and with the growth of LED and HID headlights, even unlit highways are trending this way.
(Score: 2) by Foobar Bazbot on Friday December 09 2016, @03:57AM
That was me; accidentally ACed it.
(Score: 2) by Immerman on Thursday December 08 2016, @07:22PM
Fewer photons, but probably roughly the same power, which is likely the more important consideration (not knowing the exact physics powering the human eye). Still, you're right, while they might brighten a borderline starlit scene a bit (assuming they don't attenuate visible light) they're probably not going to do a whole lot for you if you can't see anything to begin with. On the other hand, if you give your eyes a chance to adjust you can actually see quite a bit by starlight, especially using your peripheral vision which has more low-light sensitive rods, o they could still be useful.
There's also the possibility, depending on efficiency and the range of frequency response they can engineer, that you could "stack" 4 layers of crystals to achieve a 16x frequency shift of the "easily seen" frequency range from 390-700nm down to 6240-11200nm, which substantial overlaps the thermal imaging range of 8000nm-15000nm, in which range people will all glow like 100W lightbulbs. You could even add in an 5th layer with a very fine "checkerboard" of additional doubling so that you could add the 12480-22400nm range, fully spanning the thermal range at the expense of halving the apparent brightness and "double-mapping" the color spectrum so each color could correspond to two different temperatures.