A systematic study on the use of Chlorophyll Fluorescence (CF) imaging in Pulsed Amplitude Modulated (PAM) for
assessing viability changes of biodeteriogen on stone artifacts has been carried out. The experimentation has been
performed on different phototrophic organisms of gravestone slabs from the monumental British Cemetery of Florence
(Italy). Since the viability of these organisms and then their chlorophyll fluorescence emission is strongly dependent on
the environmental conditions, a preliminary study on the effects of local patterns during the season was carried out. The
trend of the fluorescence quantum yield (QYmax) at different dark adapted times in different periods of the year was
determined. The results achieved in our work proves the effectiveness of the CF-PAM imaging for in situ lichen
characterizations in conservation studies and defines an optimized application protocol.