A fast mechanical chopper system is designed for use with a pulsed YAG laser in time‐resolved resonant fluorescence measurements. The firing of the laser is synchronized with the position of the chopping wheel in order to block a photomultiplier from laser scatter. With an optical mapping technique, which does not require tight focusing of the fluorescence on the chopper blade, a turn‐on time of 2 &mgr;s is obtained with a 100‐&mgr;m spectrometer slit aperture.