Femto-photography : The high speed imaging technology!


When we capture a photograph  or take a video  normally we get things that we see normally but may be with much fewer details than can be seen with our naked eyes. With this the only thing we can do is take photograph for later reference or as a memory of that moment. But what if we can take pictures which will show us more than what we can see through our eyes!

Most of the time a bullet being shot or bubble bursting happens so quickly as a wink of an eye, maybe even quicker. When a gun shot is captured in a video all we get to see is some spark or sound and the person falls down. But imagine if a camera can shoot the bullet all along its path, or the way in which water drops splashes when a bubble bursts. It will be much more breath-taking.

The image above shows the movement of light captured in the coke bottle…

Femto-photography is a term describing ultra high-speed imaging. Femto-photography of macroscopic objects was first done by a team at the MIT Media Lab lead by Ramesh Raskar. They have constructed a camera and software that can capture slow motion videos at the speed of light— literally capturing at 1 trillion frames per second. The technology is so fast that we can create slow motion videos of light in motion.

“A camera that can see around the corner”, he says. If we have a solid obstacle the view behind it will be blocked by the object and the camera can see those things which is beyond the line of sight. The way it is done is,to see around the corner, femto photography analyze scattered light.

“We bounce light off of visible parts into hidden parts and then measure the time and direction of returned light.”, he said

This way we can even see things beyond our line of sight.

The technology is called femto-photography because a segment of the image is captured with a flashlight for a few millionths of a billionth of a second (or a few femtoseconds) and an exposure time approaching a trillionth of a second.

Ramesh said to CNN that,

Photographers know that at very short exposures and even at the most sensitive setting for dark scenes, we will record barely any light. So what about in a trillionth of a second? We actually record and average millions of photos to get enough light, each photo made to look the same via carefully timed synchronization with the light pulse. So even if our exposure time is indeed nearly a trillionth of a second, to get sufficient light we must take an average. Thus, as of now, we can only record repeatable events, but this is not a fundamental limitation.

While scattering of light is usually an irritation while taking pictures with normal cameras and hence are usually avoided, this technology makes use of it to look beyond objects.

For the camera, a laser pulse is fired at a wall, and the impact of hitting the wall causes the particles of light to scatter. Some of the scattering particles return to the camera at different times. This is repeated about 60 times per image as the camera measures how long it takes for the light to travel back and where the particles land. An algorithm then crunches the data to reconstruct the hidden image. This technique even allows us to see a three-dimensional object such as a mock-up of running person. – CNN

Future Scope

This technology to look around the corner will be a great boon in many fields and may also bring solution to many current problems

Example : If it is used in cars, we can get notified of any approaching vehicle along a curve or a bend;

We will be able to get images over depths of our body without Xrays;

We may also use it to look inside burning buildings to find trapped people  etc.

Once it comes in to practise the future scope can go beyond our imaginations.

Video :

 About Ramesh Raskar

Associate Professor at MIT Media Lab, he joined the Media Lab from Mitsubishi Electric Research Laboratories in 2008 as head of the Lab’s Camera Culture research group. In 2004, Raskar received the TR100 Award from Technology Review, in 2003, the Global Indus Technovator Award, instituted at MIT to recognize the top 20 Indian technology innovators worldwide. In 2009, he was awarded a Sloan Research Fellowship. In 2010, the DARPA Young Faculty award. He holds more than 40 US patents, and has received four Mitsubishi Electric Invention Awards. He is currently co-authoring a book on computational photography.



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