Swept frequency fluorometer

A method for monitoring environmental water quality by identifying a fluorescence species-of-interest in a water sample that contains overlapping fluorescence species, comprising:

• receiving, with a signal processor or processing module forming part of a fluorometer, signaling containing information about excitation light reflected off one or more fluorescence species-of-interest in a water sample, the excitation light having a modulation frequency and being swept across a variable frequency range from an initial modulation frequency fi to a final modulation frequency ff, the information including a characteristic optical frequency corresponding to a fluorescence species-of-interest in the water sample, and a characteristic/lifetime optical frequency corresponding to a distinct fluorescence lifetime in which the fluorescence species-of-interest remains in an excited state, the modulation frequency being swept across the variable frequency range including the characteristic optical frequency corresponding to the fluorescence species-of-interest in the water sample, and also including a midpoint of a relative phase transition at 45 degrees corresponding to the characteristic/lifetime optical frequency of the fluorescence species-of-interest;
• and
• providing, with the signal processor or processing module, corresponding signaling containing information about an identity of the fluorescence species-of-interest detected and distinguished from overlapping fluorescence species in the water sample using the characteristic/lifetime optical frequency, based upon the signaling received.

A swept frequency fluorometer for monitoring environmental water quality by identifying a fluorescence species-of-interest in a water sample that contains overlapping fluorescence species, comprising:

• a light source configured to provide excitation light on a water sample having one or more fluorescence species-of-interest, the excitation light having a modulation frequency and being swept across a variable frequency range from an initial frequency fi to a final frequency of ff;
• the modulation frequency being swept across the variable frequency range including the characteristic optical frequency corresponding to the fluorescence species-of-interest in the water sample, and also including a midpoint of a relative phase transition at 45 degrees corresponding to the characteristic/lifetime optical frequency of the fluorescence species-of-interest;
• a light sensor configured to sense the excitation light reflected off the fluorescence species-of-interest in the water sample and provide signaling containing information about the excitation light reflected off the one or more fluorescence species-of-interest in the water sample, the information including a characteristic optical frequency corresponding to a fluorescence species-of-interest in the water sample, and a characteristic/lifetime optical frequency corresponding to a distinct fluorescence lifetime in which the fluorescence species-of-interest remains in an excited state;
• and
• a signal processor or processing module configured to:
• receive the signaling, and
• provide corresponding signaling containing information about an identity of the fluorescence species-of-interest detected and distinguished from overlapping fluorescence species in the water sample using the characteristic/lifetime optical frequency, based upon the signaling received.