Defect inspection method and device therefor

A defect inspection device comprising:

• a table unit on which a sample is placed, the table unit being rotatable;
• a light source unit configured to emit a pulse laser;
• an illumination optical unit configured to divide a pulse of the pulse laser emitted from the light source unit to apply the divided-pulse pulse laser to the sample placed on the table unit;
• a detection optical unit configured to detect light reflected off the sample to which the divided-pulse pulse laser is applied by the illumination optical unit;
• a signal processing unit configured to process an output signal from the detection optical unit detecting the reflected light to detect a defect on the sample;
• and
• an output unit configured to output a result processed at the signal processing unit on a display screen,
• wherein the illumination optical unit includes:
• a pulse dividing unit configured to divide a pulse of the pulse laser emitted from the light source unit;
• a first beam monitor unit configured to monitor a barycentric position of light intensity of the divided-pulse pulse laser emitted from the pulse dividing unit;
• and
• a light intensity barycentric position adjusting unit configured to adjust the barycentric position of the light intensity of the divided-pulse pulse laser monitored at the first beam monitor unit.