2. Fast" class devices

2.1 Camera

As soon as an event occurs in less than a tenth of a second, human memory is unable to retain it. In such cases, instant photography can be used to record the data required for later examination. The recorded event is frozen, either by using a fast shutter, or by illuminating the object field with a brief light (exposure time between a fraction of a second and a microsecond for gas discharge lamps, and between a microsecond and a picosecond for lasers).

A sequence of successive images with short exposure times, superimposed on the same support (photographic or other), constitutes a stroboscopic recording. In this case, the shutter or pulsed light source operates at a regularly recurring rate for a given duration.

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