5 ms·
Light captured at 100B frames per second
- 0942v8653 12y ago> With CUP, the photons necessary to take an image are blasted through a beam splitter and then through a tube that has several tiny mirrors. These photons are converted into electrons, which encode the data you want captured—namely the time and space data necessary to create an image. Can photons actually be converted to electrons? I've never heard of anything like this. Very interesting.
- irremediable 12y agoI've possibly missed the point of what you're asking, but... surely it's obvious that photons can be converted to electrons, given that's what a photodiode does and that's how digital cameras work?
- wyager 12y ago>surely it's obvious that photons can be converted to electrons, given that's what a photodiode does and that's how digital cameras work? This is a common misconception. Both of those use light to facilitate electron excitation, but neither of them actually convert photons into electrons. The electrons are already there.
- irremediable 12y agoAh, so that's how I missed the point of what he was saying. I know how photodiodes work -- I was just struggling with the semantics of "conversion".
- wyager 12y ago>Can photons actually be converted to electrons? They can, but that's not what they actually mean here. In this case, it would be more accurate to say that the energy of the photon is being used to excite an already existing electron. As for creating electrons from photons: if you collide two photons at the correct energy level, you can get an electron-positron pair. This is a very high-energy process, and not how cameras work.
- jacquesm 12y agoMore accurately, these photons then excite electrons to a higher valence band and when those electrons fall back they give off a tiny electric current. (Either that, or another photon! see: http://www.reddit.com/r/askscience/comments/141pip/how_do_mirrors_work_on_an_atomic_level_why_is_the/ http://www.reddit.com/r/askscience/comments/141pip/how_do_mi... )
- yk 12y agoThey can ( or more precisely into positron electron pairs), but only at much higher energies ( so for example gamma rays). Most likely here some effect, for example photo-electric effect, where you can reconstruct the original photon from the electron, so that you only transfer the information of the photon.
- deleted 12y ago[deleted]
- Retra 12y agoThe photons are probably actually being converted into electric current, as a photodiode, photomultiplier, or solar panel would do.
- orbifold 12y agoOne way is via Photomultiplier http://en.wikipedia.org/wiki/Photomultiplier http://en.wikipedia.org/wiki/Photomultiplier essentially the photoelectric effect is used to create a cascade of electrons, the created current can be measured and related to the energy of the original photon (which is h * f, where h is Planck's constant and f = c/lambda is the light frequency.)
- mikegerwitz 12y agoI'm a Nature subscriber; here's some information from the paper: > To record events occurring at subnanosecond scale, currently the most effective approach is to use a streak camera, that is, an ultrafast photodetection system that transforms the temporal profile of a light signal into a spatial profile by shearing photoelectrons perpendicularly to their direction of travel with a time-varying voltage. It references: Guide. to Streak Cameras http://www.hamamatsu.com/resources/pdf/sys/e_streakh.pdf (Hamamatsu Corp., Hamamatsu City, Japan, 2002) From that PDF: > The incident light on the photocathode is converted into a number of electrons proportional to the intensity of the light, so that these four optical pulses are converted sequentially into electrons. They then pass through a pair of accelerating electrodes, where they are accelerated and bombarded against a phosphor screen. The paper does present a new method, but they are still using a streak camera: > To overcome this limitation, here we present CUP (Fig. 1), which can provide 2D dynamic imaging using a streak camera without employing any mechanical or optical scanning mechanism with a single exposure. --- I do not know anything about the topic, so I can't answer any questions. I was fascinated by the paper back in December when it was published---I'm curious to see eventual applications.
- dperfect 12y agoI find it interesting that these cameras and videos claim to capture photons as they travel through the air. Don't the photons still have to bounce off something (toward the camera) in order to be imaged by the camera? In other words, can we really "see" the photons/light in the various positions of its apparent journey, or are we still looking at a portion of the photons that have reflected off other particles (such as dust in the air) and made their way to the camera?
- wyager 12y agoEven without dust in the air, you have things like Rayleigh scattering. But yes, we only "see" the photons that were deflected from their original path.
- runeks 12y ago> I find it interesting that these cameras and videos claim to capture photons as they travel through the air. Where do they claim that? A camera needs light to hit a sensor. It can't "sense" the presence of a photon at some arbitrary point in space. That being said, I just bought a 5 mW green laser pointer, which is quite fun to play with. If you point it so the beam is in front of a dark background, you can actually see the light ray. So if we filmed this laser pointer, using the camera in question, we should be able to literally see the light ray move towards the object it's pointed at.
- partition 12y agoIs the blotchiness due to uncertainty principle or sensor imperfections? Both maybe?
- nsajko 12y agohttps://news.ycombinator.com/item?id=8709920 https://news.ycombinator.com/item?id=8709920 is the same story, posted 42 days ago.
- cornstalks 12y agoAs is https://news.ycombinator.com/item?id=8700239 https://news.ycombinator.com/item?id=8700239 from 44 days ago.
- icantthinkofone 12y agoAnd also the story I posted 11 days ago.
- avinassh 12y agobut this submission did not get enough upvotes nor was on front page. Why so
- lisper 12y agoBecause whether a story makes it onto the front page is a total crap shoot. It depends entirely on whether anyone is looking at the new page in the 30-60 minutes immediately after you submit.
- rjtavares 12y agoBecause success, both for startups and for HN submissions, is highly affected by chance.
- Gurkenmaster 12y agoSo HN is bascicially a startup simulator for side projects?
- deegles 12y agoI'm imagining now a system where users with lots of karma can "invest" in posts they think should be on the front page, incubator style. If they make it to the front page it's an "IPO" of sorts and they get a return on the other users votes.
- elwell 12y agoIf I remember correctly, these devices are capturing multiple photons over a similar path; not a single photon's journey.
- zuck9 12y agoThat's about 105 years of a normal movie if you're going to watch one second of it completely.
- kingkawn 12y agoevery day feels more closer and closer to everything getting insanely cool all at once