At that speed, you can see things that you shouldn’t be able to see at all, things that the camera isn’t actually pointing at. Wherever light has been, as it bounces around our world, it can tell us a story about its journey, letting us ‘see around corners’
To do this, you need to build a camera that is able to listen to the stories that photons can tell about where they’ve been on their travels.
Ramesh Raskar: Looking Around Corners: New Opportunities in Femto-Photography
We have built a camera that can look around corners and beyond the line of sight.
The camera uses light that travels from the object to the camera indirectly, by reflecting off walls or other obstacles, to reconstruct a 3D shape.
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.
An earlier prototype was built in collaboration with Prof. Joe Paradiso at MIT Media Lab and Prof. Neil Gershenfeld at the Center for Bits and Atoms 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 the equivalent of close to 1 trillion frames per second.
Because of this high speed, the camera is aware of the time it takes for the light to travel through the scene.
This information is then used to reconstruct shape of objects that are visible from the position of the wall, but not from the laser or camera.
Potential applications include search and rescue planning in hazardous conditions, collision avoidance for cars, and robots in industrial environments.
Transient imaging also has significant potential benefits in medical imaging that could allow endoscopes to view around obstacles inside the human body.
The new invention, which we call femto-photography, consists of femtosecond laser illumination, picosecond-accurate detectors and mathematical inversion techniques.
By emitting short laser pulses and analyzing multi-bounce reflections we can estimate hidden geometry.
In transient light transport, we account for the fact that speed of light is finite.
Light travels ~1 foot/nanosecond and by sampling the light at pico-second resolution, we can estimate shapes with centimeter accuracy.
Ramesh Raskar joined the Media Lab from Mitsubishi Electric Research Laboratories in 2008 as head of the Lab?s Camera Culture research group.
His research interests span the fields of computational photography, inverse problems in imaging and human-computer interaction.
Recent inventions include transient imaging to look around corners (Femto-photography), next generation CAT-Scan machine, imperceptible markers for motion capture (Prakash), long distance barcodes (Bokode), touch+hover 3D interaction displays (BiDi screen), low-cost eye care devices (Netra) and new theoretical models to augment light fields (ALF) to represent wave phenomena.
He is a recipient of TR100 award from Technology Review, 2004, Global Indus Technovator Award, top 20 Indian technology innovators worldwide, 2003, Alfred P.
Sloan Research Fellowship award, 2009 and Darpa Young Faculty award, 2010.
He holds over 40 US patents and has received four Mitsubishi Electric Invention Awards.
He is currently co-authoring a book on Computational Photography.
