FIELD: measurement technology. SUBSTANCE: proposed facility includes illumination unit illuminating sheet material by clock timed excitation light. Sensor records intensity of glow emitted by sheet material both during luminous and dark phases of this clock timed excitation light. Unit processing data based on values of intensity obtained during luminous and dark phases of clock timed excitation light determines intensity of fluorescent and phosphorescent glow. To provide for maximum possible duration and high intensity of preliminary illumination sensor preferably records intensity of glow within limits and at end if process is viewed in direction of feed of section of sheet material illuminated by illumination unit. Apart from it dimensions of illuminated section of sheet material are so chosen that it exceeds value of required resolution by factor of several times. EFFECT: increased accuracy of detection. 26 cl, 3 dwg
