Stroboscope instruments are used for inspection and observation of moving parts by freezing or slowing down the action of an object.  The term "stroboscope" is an expression derived from the Greek for an instrument for the observation of single phases of fast, periodic movements.  If a fast rotating or oscillating object is illuminated with periodic light flashes so they always hit it in the same position, the object will appear stationery in the eyes of the observer.  Industrial applications include printing and textile machines, aviation and automotive.