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Stroboscopic Illumination

Imaging techniques hold the power to enable measurements of motion of arbitrarily complex structures in three dimensions. However, typical imaging methods are slow — most cameras operate at speeds of 30 or fewer frames per second. However, MEMS devices, such as the one on the right-hand side of this image, can move at frequencies ranging from DC well into the megaHertz if not gigaHertz range. To image such fast motions with slow cameras, we synchronize a light source with the stimulus driving the MEMS device, a technique called stroboscopic illumination. By changing the phase of the stimulus waveform at which the light source flashes, we obtain images of the position of the MEMS device as a function of stimulus phase. These images can be played back at any desired speed; here, the device appears to move about one cycle every two seconds.