A quantitative fluorometer for multiple fluorophores having a separate time-modulated beam of excitation light for each fluorescent target. Each beam is synchronized with a separate lock-in amplifier. The fluorophores are simultaneously excited and the combined fluorescent emission is resolved into components...http://www.google.de/patents/US5294799?utm_source=gb-gplus-sharePatent US5294799 - Apparatus for quantitative imaging of multiple fluorophores
