Detection sensitivity amendment manner null of face plate defective detection

摘要

PURPOSE:To correct the detection sensitivity to obtain accurate defect data by scanning a test plate to obtain a correction coefficient for each scanning point. CONSTITUTION:A test plate 1' to which fine particles having a certain diameter are uniformly stuck is set, and a microprocessor (MPU) 4 supplies a signal to a mirror driving circuit 5a, and a mirror 2c is oscillated by an oscillating mechanism 2e to sweep the spot of a laser beam in the X direction, and the test plate 1' is scanned in the X direction. A sensor 7 detects a scanning start point, and a light receiving system 3 subjects the detection voltage of scattered light to A/D conversion by an A/D converter 6 to input it to the MPU 4. The MPU 4 supplies a moving signal to a Y-direction moving mechanism 5b and successively moves the test plate 1' stepwise in the Y direction to perform X scanning and adds the detected voltage and divides the addition result by a number (n) of times of scanning to obtain the correction coefficient and stores it in a memory 9. Next, a glass substrate 1 is set to perform X scanning, and detected data is subjected to A/D conversion by the converter 6 and is inputted to a divider 10, and the MPU 4 inputs the correction coefficient corresponding to the position of the X scanning point to the divider, thereby correcting detected data.