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Femto-photography is a technique for recording the propagation of ultrashort pulses of light through a scene at a very high speed (up to 1013 frames per second). A femto-photograph is equivalent to an optical
Femto-photography is a technique for recording the propagation of ultrashort pulses of light through a scene at a very high speed (up to 1013 frames per second). A femto-photograph is equivalent to an optical impulse response
In signal processing and control theory, the impulse response, or impulse response function (IRF), of a dynamic system is its output when presented with a brief input signal, called an Dirac delta function, impulse (). More generally, an impulse ...
of a scene and has also been denoted by terms such as a light-in-flight recording or transient image. 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
Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
). A research team at the MIT Media Lab
The MIT Media Lab is a research laboratory at the Massachusetts Institute of Technology, growing out of MIT's Architecture Machine Group in the School of Architecture. Its research does not restrict to fixed academic disciplines, but draws from ...
led by Ramesh Raskar
Ramesh Raskar is a Massachusetts Institute of Technology Associate Professor and head of the MIT Media Lab's Camera Culture research group. Previously he worked as a Senior Research Scientist at Mitsubishi Electric Research Laboratories (MERL) ...
, together with contributors from the Graphics and Imaging Lab at the Universidad de Zaragoza
The University of Zaragoza, sometimes referred to as Saragossa University () is a public university with teaching campuses and research centres spread over the three provinces of Aragon, Spain. Founded in 1542, it is one of the oldest universiti ...
, Spain, more recently achieved a significant increase in image quality using a streak camera
A streak camera is an instrument for measuring the variation in a pulse of light's intensity with time. They are used to measure the pulse duration of some ultrafast laser systems and for applications such as time-resolved spectroscopy and LID ...
synchronized to a pulsed laser Pulsed operation of lasers refers to any laser not classified as continuous wave, so that the optical power appears in pulses of some duration at some repetition rate. Silfvast, William T. (1996). ''Laser Fundamentals'', Cambridge University Press. ...
and modified to obtain 2D images instead of just a single scanline.
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 2 seconds) during the exposure period, a figure that is in agreement with the nominal resolution of the Hamamatsu streak camera model C5680, on which their experimental setup is based. Recordings taken using the setup have reached significant spread in the mainstream media, including a presentation by Raskar at TEDGlobal
TED Conferences, LLC (Technology, Entertainment, Design) is an American-Canadian non-profit media organization that posts international talks online for free distribution under the slogan "ideas worth spreading". TED was founded by Richard Sau ...
2012. 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.
In 2013, researchers at the University of British Columbia
The University of British Columbia (UBC) is a public university, public research university with campuses near Vancouver and in Kelowna, British Columbia. Established in 1908, it is British Columbia's oldest university. The university ranks a ...
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.
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.References