Patent ID: 11193887

Abstract:
A defect detection device 10 is provided with: a laser light source 11 for irradiating laser light to a measurement region R of a surface of an inspection object S; a laser light source control unit 15 for controlling the laser light source so as to cause laser light to be outputted continuously or quasi-continuously for a time longer than a period of vibration generated in the inspection object; an interferometer (speckle shearing interferometer 14) for generating interference light in which reflected light of the laser light reflected in the measurement region and reference laser light emitted from the laser light source 11 interfere; a detector (image sensor 145) for detecting the intensity of the interference light for each point in the measurement region R; a phase shifter 143 for shifting the phase of the reflected laser light or the reference laser light; an integrated intensity pattern determination unit 16 for obtaining an integrated intensity obtained by integrating the intensity for each point over an integration time longer the period of the vibration in three or more phases, the phase being shifted by the phase shifter 143 into three or more different phases; an interference degree distribution generation unit 17 for obtaining the distribution of the degree of interference based on the integrated intensity obtained in each of the three or more phases for each point; and a defect detection unit 18 for detecting a defect in the measurement region R based on the distribution of the degree of interference in the measurement region R.