1. A method for determining time-resolved fluorescence in a layer system, comprising: applying with a laser a first electro-magnetic radiation to the layer system, wherein a pulse of the laser at a first scan position stimulates a fluorophore in each one layer of multiple layers of the layer system; detecting a second electro-magnetic radiation responsive to said first electro-magnetic radiation applied by said laser, wherein said second electro-magnetic radiation is a summary fluorescence, which is a combined responsive fluorescence from said multiple layers of the layer system simultaneously detected in a time domain over a time range in response to said pulse; analyzing with a calculator unit rising behavior of the detected summary fluorescence responsive to said pulse over said time range to allocate the detected summary fluorescence into one or more proportions at any given time, after an initial delay each proportion of the one or more proportions at said given time being attributable to a corresponding one layer of the layer system; for said each one layer of the layer system identifying a corresponding time delay after which a proportion among said one or more proportions becomes attributable to said one layer; and evaluating with a calculating unit a summary decay behavior of the detected summary fluorescence responsive to said pulse by specifying, for said each one layer, the corresponding time delay as a respective, layer-fluorescence, time-of-origin, fit parameter in a model function for approximating a time decay of responsive fluorescence for said each one layer.