An apparatus that can characterize and visualize temporal dynamics of spatial light modulators (SLM's) and flat-panel displays is constructed and evaluated by use of a commercially available SLM. The apparatus is based on the stroboscopic video sampling method and has a temporal resolution of the order of microseconds, permitting measurement of a long event (>100ms) with a high signal-to-noise ratio. Experimental results demonstrate the visualization of the temporal image sequencing and addressing in an SLM.