| 摘要 |
PURPOSE:To obtain a surface defect detecting apparatus which can correctly identify a recessed defect and an adhering foreign matter irrespective of the shape of the adhering matter. CONSTITUTION:An s-polarized light 2 is made to be incident on a glass substrate 31 at an angle of incidence (thetai=16 deg.). A low angle condenser lens 33 is placed at the position of an angle of reflection (thetas=30 deg.) to the direction of the regular reflection. An electric signal ILP of the p-polarized component of the incident light is output to an operator 51, and the total component IL is output to operators 51 and 52. On the other hand, a high angle condenser lens 34 is arranged at the position of an angle of reflection (thetaS'=60 deg.) to the direction of the regular reflection. The whole component IH of the incident light is output to the operator 52. The operators 51 and 52 calculate distinguishing parameters A (=ILP/IL) and B (=IH/IL) respectively, and send to a idendifying logic 53. The logic 53 correctly identify the recessed defect from an adhering foreign matter based on the idendification parameters A and B. |
