A novel setup for fluorescence measurements of surfaces of biological samples, in particular the plasma membrane of
living cells, is described. The method is based on splitting of a laser beam and multiple total internal reflections (TIR)
within the bottom of a microtiter plate, such that up to 96 individual samples are illuminated simultaneously by an
evanescent electromagnetic field. In general, two different screening procedures (1) High Throughput Screening (HTS)
and (2) High Content Screening (HCS) are distinguished, where in the first case a rapid measurement of large sample
numbers, and in the second case a high information content from a single sample is desired. In particular, a HCS system
for the parameters fluorescence lifetime (Fluorescence Lifetime Screening, FLiS) and fluorescence anisotropy
(Fluorescence Lifetime Polarization Screening, FLiPS) has been established and integrated into an existing HTS-system.