Frequently Asked Questions

Streak Camera

A streak camera is a unique tool that is used to measure the evolution of a linear image with very high time resolution. An ultrafast streak camera is the optical counterpart of the oscillocope with a time bandwidth that can reach 2 THz.

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Its main component is a vacuum electron tube which integrates:

A photocathode to transform the incident photons into electrons;
Electron optics to accelerate those electrons to about 260 million km/h, which is 1/4 of the speed of light and focus them on a screen;
A phosphor screen to transform each electron into many visible photons which can then be recorded by CCD camera;
A set of deflection plates to apply a linearly increasing voltage while the electrons travel between them. The temporal information contained in the electron pulse (therefore in the incident optical signal) is transformed into spatial information on the screen.

A 3-dimension image is obtained for a every optical pulse incident on the photocathode. The intensity of the signal collected on the screen corresponds to the intensity of the incident signal, the horizontal and vertical axis correspond respectively to the time and the position along the cathode.

In some applications, one can replace the spatial dimension by a spectral dimension by placing a spectrometer in front of the streak camera.

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Time Units

Nanosecond: 1 nanosecond (ps) =10^-9 second, or 1 billionth of a second.
In 1 picosecond, light travelling at 300 000 km/s, travels only 30 cm.
Picosecond: 1 picosecond (ps) =10^-12 second, or 1 millionth of 1 millionth of a second.
In 1 picosecond, light travelling at 300 000 km/s, travels only 0.3 mm.
Femtosecond: 1 femtosecond (fs) = 10^-15 second, or 1 millionth of 1 billionth of a second.