Femto-photography: Taking pictures of bullets made of light

Femto-photography is a term that derives its name from the metric scale’s prefix for one-quadrillionth. When combined with photography this division of time is small enough to see groups of light photons moving. The effect is jaw-dropping. The image seen above shows a ‘light bullet’ travelling through a water-filled soda bottle. It’s part of [Ramesh Raskar's] TED talk on imaging at 1 trillion frames per second.

The video is something of a lie. We’re not seeing one singular event, but rather a myriad of photographs of discrete events that have been stitched together into a video. But that doesn’t diminish the spectacular ability of the camera to achieve such a minuscule exposure time. In fact, that ability combined with fancy code can do another really amazing thing. It can take a photograph around a corner. A laser pulses light bullets just like the image above, but the beam is bounced off of a surface and the camera captures what light ‘echos’ back. A computer can assemble this and build a representation of what is beyond the camera’s line of sight.

You’ll find the entire talk embedded after the break.


[Thanks Pim]


  1. Tom says:

    “embedded after the break” What fucking break? The link is in line with the text body.

    • gizmoguyar says:

      The “Break” is for RSS. They add a break to control what shows up in rss readers. I use Mac Mail. So in order to see the video, I have to follow the rss address to hackaday.com (this page). It assures that they don’t loose too much traffic to their website because of RSS.

    • andar_b says:

      Besides RSS, when I visit Hackaday, and an article says ‘after the break’, it always seems to imply there is something further to read/see if I click on the article link rather than reading it on the home page. Personally, I think the term is appropriate.

    • andar_b says:

      I saw this a while back, but I don’t recall where. The problem is the ‘camera’ only captures one line of the image per exposure, dozens or hundreds of repeated pulses must be fired in order to compose a two-dimensional image. Even so, the mere fact that they can capture (even in this manner) light in transit is quite amazing.

  2. aztraph says:

    Oh My Gosh, this is wonderful! If someone hasn’t already made plans to watch a wave interference pattern develop, I would be surprised, this could easily be responsible for a few string theory breakthroughs too. the end result implications are mind boggling. put one of these in over at CERN

  3. Johnny says:

    that is neato

  4. MK says:


  5. Chris C. says:

    Saw this some time ago, I think on Next Big Future. It’s not real-time capture. Repetitive light pulses are used, each time capturing just a bit of the spatial/temporal information. As long everything is motionless and the light pulse propagation repeatable, the final result is accurate. It still was, and is, incredibly impressive; and there’s no telling what further breakthroughs will result.

  6. RandomReader says:

    wow, just wow i didnt think id see that in my life time

  7. steve says:

    That’s the same crap that the oscilloscope makers sold the people as 200 MHz digital oscilloscope two decades back: equivalent sampling. They do not have this frame rate, they only combine many many shots. The process has to be cyclic or it won’t work. By the way, the first nerve impulse was measured in exactly the same way, somewhen in 1800something. I hate this hyped up TED bullshit.

    • Isaac says:

      While I think you’ve understated the significance of this. I do agree that TED is usually stupidly hyped up marketing. “Look at us, we are making progress: pay for our research”

      There are definitely some interesting things to be gained, but never enough to intrigue me.

  8. Montaray Jack says:

    Now it is a cool setup, but I wish the press would stop misrepresenting what it really is. This will never be able to take a pciture of a speeding bullet for example, like ChrisC pointed out.

    Potentially I could see this as being useful for Hollywood to get a decent BDRF like dataset for a whole scene, (really a Bidirectional Surface Scattering Reflectance Distribution Function dataset) other than that I don’t see much usefulness.

  9. Lucas says:

    I wonder how long the “exposure time” is. I mean how many bursts do they need and how long would it take. They could probably also use more cameras to catch more data/light and reduce the time needed to gather the required data.

  10. NateOcean says:

    Why is this called femto-photography and not pico-photography? What does femto refer to here?

  11. Very interesting if true. Story is too new to make an informed decision. Recommend skepticism until other independent researchers are able to reproduce the results. There are HUGE amounts of data used to produce the movie and therefore a huge number of opportunities for error.

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