Femto-Photography:
Science Inspired
by Art
John Norris
11/26/2012
What is Femto-Photography?



Ultra high-speed photography
Can capture light (photon packets) in motion similar to
bullets in traditional high speed cameras
Current resolution capability is ≈ 1.7 ps




1 picosecond = One trillionth of a second
1,000,000,000 ps in a second
Resultant frame rate: ≈ 5E11 fps (0.5 trillion frames / second)
Light sources have extraordinarily small pulse durations



Range in magnitude from 10 – 100 fs
1 femtosecond = 1 quadrillionth of a second
That means there is 1,000,000,000,000,000 fs in a second!
How Is It Done?

Many Pre-existing Techniques



Pulsing light source



Titanium-Sapphire laser
Directed to target via mirrors
“Streak” camera






LiDAR
Optical Coherence Tomography
Not an actual camera
Scans very narrow sliver of target field
Several rotating mirrors direct photons to lens
Captures roughly a 1-D movie each scan
Computer reconstructed “average” of millions of scans
Improvement over other techniques

Captures ballistic and Indirectly reflected photons
Pump Laser
Titanium-doped
Sapphire
Target
Field
Traditional
Camera
Laser Beam
Reflector
Field
Scanning
Mirrors
Who Is Doing It?

Research group at MIT:











Ramesh Raskar, Associate Professor, MIT Media Lab; Project Director
Andreas Velten, Postdoctoral Associate, MIT Media Lab
Moungi G. Bawendi, Professor, Dept of Chemistry, MIT
Everett Lawson, MIT Media Lab
Amy Fritz, MIT Media Lab
Di Wu, MIT Media Lab and Tsinghua U.
Matt O'toole, MIT Media Lab and U. of Toronto
Diego Gutierrez, Universidad de Zaragoza
Belen Masia, MIT Media Lab and Universidad de Zaragoza
Elisa Amoros, Universidad de Zaragoza
Other Contributors: (Femto-Photography Members)




Nikhil Naik, Otkrist Gupta, Andy Bardagjy, MIT Media Lab
Ashok Veeraraghavan, Rice U.
Thomas Willwacher, Harvard U.
Kavita Bala, Shuang Zhao, Cornell U.
Dr.’s Raskar & Velten
Other Projects?
Many other scientists working in the same
field at different institutions
 Dr. Raskar and team have also contributed
to many other projects

Portable Projectors
 Glasses free 3-D displays
 Femtosecond transient Imaging


Research Publications date back to 2008
Fish Tank

Things to note:





Halo around central
pulse
Captive photons in
container material?
Surface reflection
Interference
Scattering
phenomenon
Coke Bottle

Things to note:





Halo around central pulse
Light haze trapped in air
pockets
Label Reflection
Impact and scattering
phenomenon
Reflected “glow” and
invisible packets
Length of Coke Bottle:
≈ 11 in ≈ 28 ± 1 cm
Traversal Time:
≈ 1.245 ± 0.04 ns
Frame Rate: (16s video length)
≈ 373 ± 18 billion fps (pretty
close)
Practicality and Uses

Currently quite impractical

Limited by scanning rates



Size of targets
Inability to process target motion
Potential uses in the future

Medical Imaging




Industrial/Scientific



Infinitely better than ultrasound
Maps how photons scatter volumetrically
3-D color photograph of internals!!!!
Non invasive structural testing of materials
Defect analysis
Consumer Photography
Internal Structure

Things to note:

Non-uniformities




Surface
Interior
Propagation pulsing
Optical Illusions

Unexpected behaviors
Video Contents
Rock candy, laser pulse
through orange, and
reflection off of the corner
of a “room”
References




"Visualizing Light at Trillion FPS, Camera Culture, MIT Media Lab."
Visualizing Light at Trillion FPS, Camera Culture, MIT Media
Lab. N.p., n.d. Web. 24 Nov. 2012.
<http://web.media.mit.edu/~raskar/trillionfps/>.
"Streak Camera." Wikipedia. Wikimedia Foundation, 23 Nov. 2012.
Web. 24 Nov. 2012.
<http://en.wikipedia.org/wiki/Streak_camera>.
"Optical Coherence Tomography." Wikipedia. Wikimedia
Foundation, 23 Nov. 2012. Web. 24 Nov. 2012.
<http://en.wikipedia.org/wiki/Optical_coherence_tomography>.
"Ti-sapphire Laser." Wikipedia. Wikimedia Foundation, 11 Dec.
2012. Web. 24 Nov. 2012.
<http://en.wikipedia.org/wiki/Ti-sapphire_laser>.