Streak camera
Streak cameras (smear image cameras ) are used to measure very fast processes in a time-resolved manner. By doing without a spatial dimension of the motif, they can instead depict the timeline in it. In optical spectroscopy , time resolutions in the range of a few picoseconds are required for this.
The principle of a streak camera is as follows: Two optical pulses with a time offset of Δ t strike the photocathode of the streak camera and trigger electrons there. These are accelerated and pass through a time-dependent, electric field . Since the electrons are knocked out of the photocathode at different times due to the time delay, they both pass through different electrical fields and are thus deflected to different degrees. The spatially defined separation achieved in this way can now be used to infer the temporal offset of the electrons and thus of the optical pulses.
Today's cameras deliver temporal resolutions in the range of femtoseconds . At the end of 2011, researchers at the Massachusetts Institute of Technology caused a sensation when they introduced a device based on streak camera technology that can take 600 billion images per second. With this camera z. B. observe the propagation of light or photons .
Older streak cameras used a rotating mirror to scan a gap across a film. Due to the uncertain position of the slit image at a predetermined time from the outside, these cameras provided a trigger output had also trigger the event to be photographed when the camera is triggered with an adjustable time offset be used.
Individual evidence
- ↑ Visualizing Photons in Motion at a Trillion Frames Per Second Camera Culture MIT Media Lab
- ↑ Laser and - Action! Technology Review
literature
- Wolfgang Demtröder : Laser Spectroscopy. Basics and Techniques . 5th edition. Springer-Verlag, Berlin 2007, ISBN 978-3-540-33792-8 .