CORRECTION OF BACKGROUND FOR DENSITOMETER

PURPOSE:To achieve a higher certainty in the correction of background, by storing a photometry value at each scanning stroke in a zigzag scanning system so that the minimum of photometry value data is made as value of the background during the period of the stroke. CONSTITUTION:A zigzag scanning of a fine luminous flux is performed on a spot of a sample developed separately on a thin layer plate to detect transmission or reflected light from the sample spot with a detector 1. Then, the light is inputted into a CPU 4 as absorbance data through an A/D converter 3 and stored into a data memory at each scanning stroke. A minimum data is extracted from the data memory and subtracted from data stored in the data memory as background value, thereby achieving a higher certainty in the correction of the background.