Method for measuring the fluorescence lifetime of an excited state in a sample

The method involves illuminating a sample region with an excitation pulse. A digital data sequence is generated, where the sequence is representative of a power-time profile of the pulse. A switching instant is determined from the sequence. A detection light (18) emanating from the region is detected by a detector (20). Another digital data sequence is generated, where the latter sequence is representative of a power-time profile of the detection light. Another switching instant is determined from the latter sequence, and a time difference between the two switching instants is calculated. An independent claim is also included for a device for measuring lifetime of an excited state in a sample.