Fluorescence lifetime sensor module comprising an opaque housing having a first chamber and a second chamber separated by a light barrier, further comprising: - an optical emitter arranged in the first chamber, and configured to emit through a first aperture pulses of light of a specified wavelength arranged to optically excite a fluorescent probe to be positioned within a field of view of the sensor module, - a main detector arranged in the second chamber, and configured to detect through a second aperture received photons from the fluorescent probe, - a measurement block configured to determine respective difference values representative of an arrival time of one of the received photons with respect to the emission pulses and, - a histogram block (HIST) configured to accumulate the difference values in a histogram, - a processing circuit configured to compute time-of-flight values based on an evaluation of the histogram, compute a fluorescence lifetime from the time-of-flight values and generate an output signal being indicative of the fluorescence lifetime of the fluorescent probe, and - a control unit configured to initiate pulsed emission of the optical emitter, wherein - the opaque housing is arranged on a carrier and the opaque housing comprises the light barrier which divides the housing into the first and the second chambers (CH1, CH2), - the first and second chambers (CH1, CH2) are further confined laterally by a frame body arranged in the housing, - a cover section is located opposite to the carrier and thereby covers the chambers (CH1, CH2), and - the cover section, frame body, and light barrier are comprised by a continuous piece of material, in particular, a mold material, wherein: - an optical filter is arranged above or inside the second aperture, and is configured to pass only light which is spectrally shifted with respect to the specified wavelength, and - the optical filter is fixed to the opaque housing or interchangeable, and wherein the processing circuit is configured to: - calibrate the time-of-flight values for a known distance between the fluorescence lifetime sensor module and the fluorescent probe in a measurement mode, and - compute a distance value between the fluorescence lifetime sensor module and the fluorescent probe from the time-of-flight value of light reflected at the fluorescence probe as target instead of fluorescence emission, wherein the difference values are translated into the distance value, and wherein the distance value is used to compensate for a time offset in the fluorescence lifetime measurement. - an optical emitter arranged in the first chamber, and configured to emit through a first aperture pulses of light of a specified wavelength arranged to optically excite a fluorescent probe to be positioned within a field of view of the sensor module, - a main detector arranged in the second chamber, and configured to detect through a second aperture received photons from the fluorescent probe, - a measurement block configured to determine respective difference values representative of an arrival time of one of the received photons with respect to the emission pulses and, - a histogram block (HIST) configured to accumulate the difference values in a histogram, - a processing circuit configured to compute time-of-flight values based on an evaluation of the histogram, compute a fluorescence lifetime from the time-of-flight values and generate an output signal being indicative of the fluorescence lifetime of the fluorescent probe, and - a control unit configured to initiate pulsed emission of the optical emitter, wherein - the opaque housing is arranged on a carrier and the opaque housing comprises the light barrier which divides the housing into the first and the second chambers (CH1, CH2), - the first and second chambers (CH1, CH2) are further confined laterally by a frame body arranged in the housing, - a cover section is located opposite to the carrier and thereby covers the chambers (CH1, CH2), and - the cover section, frame body, and light barrier are comprised by a continuous piece of material, in particular, a mold material, wherein: - an optical filter is arranged above or inside the second aperture, and is configured to pass only light which is spectrally shifted with respect to the specified wavelength, and - the optical filter is fixed to the opaque housing or interchangeable, and wherein the processing circuit is configured to: - calibrate the time-of-flight values for a known distance between the fluorescence lifetime sensor module and the fluorescent probe in a measurement mode, and - compute a distance value between the fluorescence lifetime sensor module and the fluorescent probe from the time-of-flight value of light reflected at the fluorescence probe as target instead of fluorescence emission, wherein the difference values are translated into the distance value, and wherein the distance value is used to compensate for a time offset in the fluorescence lifetime measurement. - calibrate the time-of-flight values for a known distance between the fluorescence lifetime sensor module and the fluorescent probe in a measurement mode, and - compute a distance value between the fluorescence lifetime sensor module and the fluorescent probe from the time-of-flight value of light reflected at the fluorescence probe as target instead of fluorescence emission, wherein the difference values are translated into the distance value, and wherein the distance value is used to compensate for a time offset in the fluorescence lifetime measurement.