Femto-photography

Femto-photography is a term used to describe a technique for recording the propagation of ultrashort pulses of light through a scene at a very high speed. A femto-photograph is equivalent to an optical impulse response of a scene and has also been denoted by terms such as a light-in-flight recording[1] or transient image.[2][3] Femto-photography of macroscopic objects was first demonstrated using a holographic process in the 1970s by Nils Abramsson at the Royal Institute of Technology (Sweden).[1] A research team at the MIT Media Lab led by Ramesh Raskar, together with contributors from the Graphics and Imaging Lab at the Universidad de Zaragoza, Spain, more recently achieved a significant increase in image quality using a streak camera synchronized to a pulsed laser and modified to obtain 2D images instead of just a single scanline.[4][5]

In their publications, Raskar's team claims to be able to capture exposures so short that light only traverses 0.6 mm (corresponding to 2 picoseconds, or 2x10−12 seconds) during the exposure period,[6] a figure that is in agreement with the nominal resolution of the Hamamatsu streak camera model C5680,[7][8] on which their experimental setup is based.[9] Recordings taken using the setup have reached significant spread in the mainstream media, including a presentation by Raskar at TEDGlobal 2012[10] Furthermore, the team was able to demonstrate the reconstruction of unknown objects "around corners", i.e., outside the line of sight of light source and camera, from femto-photographs.[9]

In 2013, researchers at the University of British Columbia demonstrated a computational technique that allows the extraction of transient images from time-of-flight sensor data without the need for ultrafast light sources or detectors.[11]

Other uses of the term

Prior to the aforementioned work, the term "femto-photography" had been used for certain proposed procedures in experimental nuclear physics.[12]

See also

References

  1. 1 2 Abramsson, Nils (1978). "Light-in-flight recording by holography". Optics Letters. 3 (4): 121–123. doi:10.1364/OL.3.000121.
  2. ↑ Smith, Adam; James Skorupski; James Davis (2008). "Transient Rendering". Technical Report, School of Engineering, University of California Santa Cruz. UCSC-SOE-08-26. Retrieved 31 July 2014.
  3. ↑ Kirmani, A.; Hutchison, T.; Davis, J.; Raskar, R. (2009). "Looking around the corner using transient imaging". IEEE 12th International Conference on Computer Vision: 159–166. doi:10.1109/ICCV.2009.5459160.
  4. ↑ "Visualizing Light at Trillion FPS, Camera Culture, MIT Media Lab". Web.media.mit.edu. 2011-12-13. doi:10.1145/2037715.2037730. Retrieved 2012-10-04.
  5. ↑ Velten, Andreas; Di Wu; Adrian Jarabo; Belen Masia; Christopher Barsi; Chinmaya Joshi; Everett Lawson; Moungi Bawendi; Diego Gutierrez; Ramesh Raskar (July 2013). "Femto-Photography: Capturing and Visualizing the Propagation of Light" (PDF). ACM Transactions on Graphics. 32 (4). Retrieved 21 November 2013.
  6. ↑ "Slow art with a trillion frames per second camera". Dl.acm.org. doi:10.1145/2037715.2037730. Retrieved 2012-10-04.
  7. ↑ Hamamatsu Corporation. "Universal Streak Camera C5680 Series - Measurements Ranging From X-Ray to Near Infrared With a Temporal Resolution of 2 ps". Retrieved 2013-11-22.
  8. ↑ Information from alldatasheet.com
  9. 1 2 Velten, Andreas; Thomas Willwacher; Otkrist Gupta; Ashok Veeraraghavan; Moungi G. Bawendi; Ramesh Raskar (20 March 2012). "Recovering three-dimensional shape around a corner using ultrafast time-of-flight imaging". Nature Communications. 3. doi:10.1038/ncomms1747.
  10. ↑ TEDGlobal 2012. "Ramesh Raskar: Imaging at a trillion frames per second | Video on". Ted.com. Retrieved 2012-10-04.
  11. ↑ Heide, Felix; Matthias B. Hullin; James Gregson; Wolfgang Heidrich. "Low-Budget Transient Imaging using Photonic Mixer Devices". In: ACM Trans. Graph. 32(4) (Proc. SIGGRAPH 2013). Retrieved 22 November 2013.
  12. ↑ "Nucleon hologram with exclusive leptoproduction". Exclusive Processes at High Momentum Transfer. May 15–18, 2002. Retrieved 4 October 2012.


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