System for in vitro detection and/or quantification by fluorometry

The invention relates to a system (1) for the in vitro detection and/or quantification, by fluorometry, of at least one analyte in a sample (E) of fluid constituting a biological material, in particular for an immunological test, including a radiation source (10), followed by an optical splitter (13) for splitting the main beam (FP) into a sample-energizing beam (FE) and a reference beam, with a first photodetector means (14) for detecting a fluorescence ray (RF) emitted by the sample and a second photodetector means (15) for the reference beam, said system also including a generator (300) outputting a sinusoidal carrier signal (SNM) and at least one digital demodulation signal (SINE, COSINE), and a digital processing means for processing, by demodulation, the signals from the two photodetector means in order to extract a fluorescence value (VALF); that is characteristic of the amplitude of the fluorescence ray and a second reference value (VALR) that is characteristic of the amplitude of the reference beam.