Frederiksen

Very short but powerful pulses of light are emitted from the box.  When the light pulses hit the special retroflective foil of the reflector they are directed back towards the source – with no need for tedious adjustments.  Via a beamsplitter, the light pulses finally hit a high speed photodiode, converting them into electric pulses to be displayed on an oscilloscope.  A separate synchronization signal marks the time of pulse emission and constitutes a reference for timing the pulses.