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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

The End of Megapixels

Abstract of the link:

[h=2]Abstract[/h] We have built an imaging solution that allows us to visualize propagation of light. The effective exposure time of each frame is two trillionths of a second and the resultant visualization depicts the movement of light at roughly half a trillion frames per second. Direct recording of reflected or scattered light at such a frame rate with sufficient brightness is nearly impossible. We use an indirect 'stroboscopic' method that records millions of repeated measurements by careful scanning in time and viewpoints. Then we rearrange the data to create a 'movie' of a nanosecond long event.

The device has been developed by the MIT Media Lab’s Camera Culture group in collaboration with Bawendi Lab in the Department of Chemistry at MIT. A laser pulse that lasts less than one trillionth of a second is used as a flash and the light returning from the scene is collected by a camera at a rate equivalent to roughly half a trillion frames per second. However, due to very short exposure times (roughly two trillionth of a second) and a narrow field of view of the camera, the video is captured over several minutes by repeated and periodic sampling.

The new technique, which we call Femto Photography, consists of femtosecond laser illumination, picosecond-accurate detectors and mathematical reconstruction techniques. Our light source is a Titanium Sapphire laser that emits pulses at regular intervals every ~13 nanoseconds. These pulses illuminate the scene, and also trigger our picosecond accurate streak tube which captures the light returned from the scene. The streak camera has a reasonable field of view in horizontal direction but very narrow (roughly equivalent to one scan line) in vertical dimension. At every recording, we can only record a '1D movie' of this narrow field of view. In the movie, we record roughly 480 frames and each frame has a roughly 1.71 picosecond exposure time. Through a system of mirrors, we orient the view of the camera towards different parts of the object and capture a movie for each view. We maintain a fixed delay between the laser pulse and our movie starttime. Finally, our algorithm uses this captured data to compose a single 2D movie of roughly 480 frames each with an effective exposure time of 1.71 picoseconds.

Beyond the potential in artistic and educational visualization, applications include industrial imaging to analyze faults and material properties, scientific imaging for understanding ultrafast processes and medical imaging to reconstruct sub-surface elements, i.e., 'ultrasound with light'. In addition, the photon path analysis will allow new forms of computational photography, e.g., to render and re-light photos using computer graphics techniques.
Click to expand...
 
Peter Dmitriyev said:
i don't get it, this seems to be about frame rate not megapixels
Click to expand...

It's not about either. It's about capturing light emitted by returning laser pulses and doing it fast enough and accurately enough where the exposure can be timed at different intervals in relation to the laser plulses. And doing it enough times where all the results can be averaged together to make images, and in turn a movie, that represents how light propagates through an environment.. While the camera being used is indeed fast in terms of capturing individual exposures, the field of view is so small, it's analogous to a pixel. The hardware doing all this is quite large and the area it photographs is a relatively small tabletop. This is not so much about camera technology, but using available technology to study the behavior and motion of light. Visually showing us a composite representation of how light moves.
 
Agree with Jeff, when reading more about it they are actually not filming in the speed of light...they shoot super short laser pulses and takes snap shot of them and put it together as a film... it not the same little light flash in the different frames of the film it's actually one individual pulse for each frame... so the guy is not even close to explain what he is really doing. which I think is a bit sad.. It's cool what they do but they made it sound a lot more cooler than it actually is.
 
gated arrays

gated arrays

For reference.
Gated arrays were used in covert military surveillance in the nineties.
A plus of light is fired from a laser and a camera is synchronised to see the pulse at a particular time.
An example would be firing a pulse into a room through net curtains, the camera takes it exposure once the light is inside the room.
Another example is lighting the interior of cars through heavily tinted windows so you can see who is inside.
The laser was IR of course and camera was image intensified.


Mike Brennan
 
Impressive. Hope i'll still be on earth when this camera will start selling.
 
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