Method for Determining the Intensity of the Luminescence of Markers Present in a Test Field

A method for determining the intensity of the luminescence of markers present in a test field, with a known time constant representative of the time course of the luminescence, wherein the test field is reflective for excitation light in at least a partial region, and wherein the method comprises

• illuminating the test field with pulsed excitation light that has a pulse period and a pulse duration,
• recording the pulsed illuminated test field by means of a camera comprising a rolling shutter image sensor with a 2D photodiode array, wherein the image sensor is operated using
• an image period which is the reciprocal of the refresh rate,
• a line frequency for the sequential switching of the activation of a line of photodiodes of the 2D photodiode array,
• an integration duration for which a line remains switched active, and an image recording duration within which all lines of photodiodes of the 2D photodiode array have been activated once,
• wherein each photodiode provides a signal representative of the respective intensity of received light,
• wherein the pulse period of the excitation light is at most equal to the image recording duration of the image sensor,
• wherein as a result of the pulsed illumination by the camera, images of the test field are recorded which have alternately successive parallel light and dark stripes, the bright stripes arising as a result of reflection of the excitation light from the test field and as a result of the luminescence of potential markers and/or as a result of potential autoluminescence of the test field, and the dark stripes arising as a result of the excitation light being absent in an illumination pause between two successive illumination pulses, and
• said stripes are stationary in the images if the pulse period is an integer fraction of the image period, and shift between successive images if the pulse period is a non-integer fraction of the image period,
• wherein, when markers are present in the test field, at least some of the photodiodes of some rows of the 2D photodiode array detect luminescence within the dark stripes, which appears in one or more of the dark stripes of the images as line or band regions which extend with decaying intensity transversely to the extension of the light and dark stripes starting from a bright stripe to the adjacent dark stripe following the bright stripe in time, and
• wherein the decaying brightness of the luminescence within a dark stripe and the known time constant defining the time course of the luminescence lifetime are used to infer the intensity of the luminescence at a given reference time.