We needed an easy to install, triggerable, intensity-modulated light source. An LED is by far the easiest and cheapest solution. Furthermore, small latencies between triggered light pulses are crucial for the analysis of the kinetics of measurements. We used the CoolLED pE-300ultra, which meets these requirements. Another great advantage of this product lies in its versatility for use in upcoming experiments covering different wavelengths. Its flexibility allows the performance of very complex experimental protocols.