Wednesday, January 28, 2015

ST SPAD Array Captures Light in Flight

ST 32x32 SPAD array developed under EU funded FP6 project Megaframe with University of Edinburgh and partners is the basis of Heriot-Watt University 20 billion fps-fast camera. The open access Nature Communications' paper "Single-photon sensitive light-in-fight imaging" by Genevieve Gariepy, Nikola Krstajić, Robert Henderson, Chunyong Li, Robert Thomson, Gerald Buller, Barmak Heshmat, Ramesh Raskar, Jonathan Leach & Daniele Faccio.

A laser pulse is reflecting off multiple mirrors, passing three times
across the field of view of the SPAD camera (35 35 cm2).
The same laser is used to create a trigger sent to the camera.
The SPAD camera collects scattered photons from the laser pulse.
The field of view does not contain the mirrors because the
scattered light coming from the mirror surfaces is much more
intense than the Rayleigh-scattered light during propagation.
The histogram indicates the time of arrival of the laser pulse as
measured by pixel (22, 21). The time frames, shown at 0, 1, 2, 3
and 4 ns, show the evolution of the pulse in time as it propagates
across the scene. The integration of all frames gives the total
path followed by the light, similarly to what can be acquired
by an EMCCD camera at maximum gain for an exposure time of 7 s.

A Youtube video shows the light propagation process:

New Scientist too publishes an article on the new camera.

Thanks to LG for the link!

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