A stroboscope designed to observe pulsars in the optical spectrum is presented .
The absolute phase of the stroboscope is synchronized to better than 2.5 \mu s with the known radio ephemerides for a given pulsar .
The absolute timing is provided by the GPS clock .
With such a device phase resolved photometry of pulsars can be performed .
We demonstrate the instrument ’ s capabilities with the results of a set of observations of the Crab pulsar , the brightest of the known optical pulsars , with a visual magnitude of 16.5 , and a rotational frequency of \sim 29 Hz .