"In this Letter, we present a laser probe-based method that unifies the aforementioned aspects and is capable of producing a video sequence of non-repetitive dynamic events at femtosecond timescales and beyond for spectroscopy. Our method, called Frequency Recognition Algorithm for Multiple Exposures (FRAME), allows acquisition of a series of laser-induced images at frame rates that are limited only by the laser pulse duration. Here, we used femtosecond laser pulses to demonstrate videography with record high sub-ps (THz) temporal resolution, although attosecond laser pulses could, in principle, increase the frame rate into the PHz regime. The novelty of the FRAME concept lies in superimposing a structural code onto the illumination to encrypt a single event that is then deciphered in the data post-processing. Because each image in the video sequence is extracted by using a unique spatial code, the method does not rely on a specific optical wavelength or laser bandwidth, and hence can be used for spectroscopic measurements. Here, we provide a proof-of-principle demonstration of our method by performing imaging light-in-flight – often regarded as the gold standard experiment for ultrafast imaging at 5 THz, a timescale on which even light appears stationary on a macroscopic scale."
Although the paper talks about 200fs temporal resolution, the University demo shows 50fs time step between the frames of their video:
Can anyone tell me what this ball of fire actually is? I suppose we are seeing photon scattering or secondary photons of some sort. Why does it look spherical? How many photons are in the pulse? The translated youtube caption says:
ReplyDelete"This clip shows how light - a collection of photons - travels a distance corresponding to the thickness of a paper. In reality, the event occurs only on a picnic, but has slowed down a billion times."
Eric I think Video #2 is a real version of the Animation shown in Video #1 at time 0:11.
ReplyDeleteWhat photons are reaching the camera?
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