Four-dimensional flash trajectory imaging using time-delay-modulated range-gated viewing

We present a four-dimensional flash trajectory imaging method to image object trajectories over time in three-dimensional space. In the method, time-delay-modulated range-gated viewing with multiple exposures is presented so that the time evolution of object trajectories free from background interference is directly given without complicated image processing and the motion parameters of objects can be estimated. The method is demonstrated by a ball oscillating as a pendulum.