SLIT LIGHT LUMINANCE DISTRIBUTION DESIGN METHOD AND OPTICAL CUTTING IRREGULARITY FLAW DETECTION DEVICE

PROBLEM TO BE SOLVED: To provide a slit light luminance distribution design method and an optical cutting irregularity flaw detection device for performing stable optical cutting irregularity flaw detection corresponding to the range widening and speeding-up of surface flaw inspection.SOLUTION: The slit light luminance distribution design method in an optical cutting irregularity flaw detection method for irradiating a measurement object with a slit light, and for picking up the image of a reflected light from an angle which is different from that of a slit light source, and for detecting an irregularity flaw based on the pickup image includes: an average reflection rate measurement process of measuring the average reflection rate of the measurement object to the direction of an image pickup device using a slit light source A whose luminance distribution is already known; and a slit light luminance distribution calculation process of calculating the optimal luminance distribution of the slight light source for picking up the image of the reflected light as uniform luminance based on the measured average reflection rate.