"同步闪光装置" can be translated as "synchronous flashing device" or "synchronized flashing unit".
"Synchronous" emphasizes the simultaneous or coordinated action, which is a key characteristic of such devices.
"Flashing" clearly describes the function of emitting light in rapid, intermittent bursts.
"Device" or "unit" refers to the physical apparatus performing this function.
Both translations are accurate and commonly used in technical and engineering contexts.