In-situ monitoring of biological growth on stone

A Scanning Fluorescence Microscope system for quantifying and mapping biological growth on stone is described. The system uses 488 nm light from an Argon-ion laser to excite the 685 nm fluorescence from the Chlorophyll-a in the algae and uses this as the means of mapping the biological material. The measured 685 nm fluorescence is shown to increase linearly with the quantity of algae on the stone surface. Application of the system to study the effectiveness of biocide treatment for the control of algae on stone is reported.