Method for determining the thickness of one or more layers of a sample stack of layers (700, 702) or other properties influencing the intensity of light reflected by the sample stack with an assembly comprising a light source for illuminating the sample stack of layers (700, 702) and a camera with a detector for detecting the intensity of light reflected by the sample stack of layers in defined wavelength ranges (340, 350, 360, 370, 380, 390), the method comprising the steps of: (a) illuminating the sample stack of layers (700, 702) with light (703, 704, 50) from the light source; (b) detecting the intensity of light reflected by the sample stack of layers (700, 702) with the detector in different wavelength ranges (340, 350, 360, 370, 380, 390); and (c) determining the thickness or other property from the intensity detected by the detector; wherein (d) the detector is an array detector with a plurality of detector elements in lines and columns; (e) an image of the sample stack of layers is generated on the detector; (f) the detector comprises a plurality of sections in the form of parallel stripes (761, 762, 763, 764, 765, 766), the stripes detecting the intensity of light reflected by the sample stack of layers simultaneously; (g) light of one selected wavelength range (340, 350, 360, 370, 380, 390) only is detected by each of the plurality of sections (761, 762, 763, 764, 765, 766) of the detector and a calculation is performed separately for each detector element of the detector to determine the thickness or other property at the detected point; and (h) a movement of the image of the sample stack of layers on the detector or of the parallel stripes (761, 762, 763, 764, 765, 766) is generated in a direction perpendicular to the longitudinal direction of the parallel stripes such that each point of the inspected sample stack of layers is detected at least once in each of the different wavelength ranges (340, 350, 360, 370, 380, 390). (a) illuminating the sample stack of layers (700, 702) with light (703, 704, 50) from the light source; (b) detecting the intensity of light reflected by the sample stack of layers (700, 702) with the detector in different wavelength ranges (340, 350, 360, 370, 380, 390); and (c) determining the thickness or other property from the intensity detected by the detector; wherein (d) the detector is an array detector with a plurality of detector elements in lines and columns; (e) an image of the sample stack of layers is generated on the detector; (f) the detector comprises a plurality of sections in the form of parallel stripes (761, 762, 763, 764, 765, 766), the stripes detecting the intensity of light reflected by the sample stack of layers simultaneously; (g) light of one selected wavelength range (340, 350, 360, 370, 380, 390) only is detected by each of the plurality of sections (761, 762, 763, 764, 765, 766) of the detector and a calculation is performed separately for each detector element of the detector to determine the thickness or other property at the detected point; and (h) a movement of the image of the sample stack of layers on the detector or of the parallel stripes (761, 762, 763, 764, 765, 766) is generated in a direction perpendicular to the longitudinal direction of the parallel stripes such that each point of the inspected sample stack of layers is detected at least once in each of the different wavelength ranges (340, 350, 360, 370, 380, 390).