Hence, to gain in-situ direct flow data from fuel cells, which is inevitable for CFD simulations or even more complicated numerical models of a fuel cell stack, in this work the LDA-technique is modified in a way that spatial resolution is increased and measurements close to walls are possible and which is suitable for any kind of pipe branching system with optical access. Additionally, methods are presented to provide optical access to the specific fluidic system of the stack and to generate suitable tracer particles for the flow measurements.