~Fluorescence Labelling This invention generally relates to techniques fo r fluorescence labelling, and to methods, apparatus and computer program cod e for processing fluorescence signal data. A method of determining respectiv e first and second degree-of-labelling signals for different respective firs t and second fluorophores associated with a common entity (a probe or a targ et), the method comprising: determining a first fluorescence signal from sai d first and second fluorophores under first conditions (illumination wavelen gth),- determining a second fluorescence signal from said first and second f luorophores under second conditions (illumination wavelength) different to s aid first conditions; and determining said first and second degree-of-labell ing signals for said first and second fluorophores from said first and secon d fluorescence signals; and wherein said determining of said first and secon d degree-of-labelling signals is responsive to at least one coupling value ( cl2;c21) representing a coupling of energy between said fluorophores.
FLUORESCENCE LABELLING