An experimental technique is demonstrated whereby the dynamic deflection of a thin plate or combination of plates, impulsively loaded by the blast of an explosive charge, can be characterized. A blast pendulum measures the resulting impulse simultaneously. The technique utilizes a cylindrical adapter that is fixed onto the blast pendulum into which a helical array of laser diode and receiver pairs are fitted. The output of the receivers is electronically coupled and a cascade voltage plot is obtained as the deforming plate interrupts the aligned light beams. It is found that the technique yields good results of the dynamic motion of the plates as long as the deformation of the specimen is symmetrical.