Detection of Surface Tilt Defect by Photoacoustic Method
Details
In this study, the imaging of simulated surface defect using a photoacoustic (PA) microscope has been demonstrated. The surface tilt defect was the slit-type simulated defect, whose length was fixed to be about 4.0mm. The surface tilt defect with a width of 0.3 mm was introduced into the specimen by mechanical processing. The depth and angle values of the surface defects were 0.3 mm and 60, 70, 80 and 90 degrees in nominal value, respectively. By defining the "degree of asymmetry" as the ratio of the difference between two peaks of phase signal distribution to the height of their mean value from the background, the correlation coefficient between tilt angle and the degree of asymmetry showed the value of 0.997.
