A system for quantifying fluorescence elicited on a substance or sample. The system has an excitation light source configured to direct light to an waveguide network. The network has a probe tip adapted to transmit excitation light to the sample and receive fluorescence light elicited from the sample. A detector is configured to receive fluorescence light from the waveguide network and output a signal corresponding to the fluorescence light power, and a control system including a memory component configured to store signal to noise ratio threshold values.