Light-in-flight imaging — a set of techniques to visualize propagation of

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

through different media.

History and techniques

Light was first captured in its flight by N. Abramson in 1978, who used a

holographic Holography is a technique that allows a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interfe ...

technique to record the

wavefront In physics, the wavefront of a time-varying ''wave field (physics), field'' is the set (locus (mathematics), locus) of all point (geometry), points having the same ''phase (waves), phase''. The term is generally meaningful only for fields that, a ...

of a pulse propagating and being

scattered Scattered may refer to: Music * ''Scattered'' (album), a 2010 album by The Handsome Family * "Scattered" (The Kinks song), 1993 * "Scattered", a song by Ace Young * "Scattered", a song by Lauren Jauregui * "Scattered", a song by Green Day from ...

by a white-painted screen placed in its path. This high-speed recording technique allowed the dynamic observation of light phenomena like

reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, mirror-like reflection of waves from a surface *** Mirror image, a reflection in a mirror or in water ** Diffuse r ...

interference Interference is the act of interfering, invading, or poaching. Interference may also refer to: Communications * Interference (communication), anything which alters, modifies, or disrupts a message * Adjacent-channel interference, caused by extra ...

and focusing that are normally observed statically. More recently, light-in-flight holography has been performed in a scattering medium rather than using a reflective screen. Light can also be captured in motion in a scattering medium using a streak camera that has

picosecond A picosecond (abbreviated as ps) is a unit of time in the International System of Units (SI) equal to 10−12 or (one trillionth) of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000 ...

temporal resolution Temporal resolution (TR) refers to the discrete resolution of a measurement with respect to time. It is defined as the amount of time needed to revisit and acquire data for exactly the same location. When applied to remote sensing, this amount of ...

, thus removing the need for

interferometry Interferometry is a technique which uses the ''interference (wave propagation), interference'' of Superposition principle, superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important inves ...

and

coherent Coherence is, in general, a state or situation in which all the parts or ideas fit together well so that they form a united whole. More specifically, coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics ...

illumination but requires additional hardware to raster scan the two-dimensional (2D) scene, which increases the acquisition time to hours. A few other techniques possess the temporal resolution to observe light in motion as it illuminates a scene, such as photonic mixer devices based on modulated illumination, albeit with a temporal resolution limited to a few

nanosecond A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit (e ...

s. Alternatively, time-encoded amplified imaging can record images at the repetition rate of a

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

by exploiting wavelength-encoded illumination of a scene and amplified detection through a dispersive fibre, albeit with 160 ns temporal and spatial resolution. Recent studies based on

computer tomography A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

using data from multiple probe pulses enabled reconstruction of picosecond pulse propagation phenomena in condensed media. In 2015 a method to visualize events evolving on picosecond time scales based on single-photon detector arrays has been demonstrated.{{cite journal , last=Gariepy , first=Genevieve , last2=Krstajić , first2=Nikola , last3=Henderson , first3=Robert , last4=Li , first4=Chunyong , last5=Thomson , first5=Robert R. , last6=Buller , first6=Gerald S. , last7=Heshmat , first7=Barmak , last8=Raskar , first8=Ramesh , last9=Leach , first9=Jonathan , last10=Faccio , first10=Daniele , title=Single-photon sensitive light-in-fight imaging , journal=Nature Communications , publisher=Springer Science and Business Media LLC , volume=6 , issue=1 , date=2015-01-27 , issn=2041-1723 , doi=10.1038/ncomms7021 , page=6021, doi-access=free, hdl=1721.1/96779 , hdl-access=free

References

Film and video technology Light Articles containing video clips

History and techniques

See also

References