The disclosure generally relates to a system for detecting a change in an attribute of a substance. The system may include a photon source for producing a first of a plurality of photons which interact with the substance while an attribute of the substance changes to produce a second plurality of photons. The system may also include a filter for receiving the collected photons and providing filtered photons; a photon detector for receiving the filtered photons and obtaining therefrom a spectrum of the substance; and a processor for detecting an aspect of the filtered photons wherein the aspect of the filtered photons is the function of the attribute of the substance.