Inspection device

Abstract

Abstract PURPOSE:To automate an operation and to enhance the reliability of an inspected result by a method wherein the intensity of reflected light or scattered light generated by an object to be inspected which is irradiated with the inspection light is compared with a threshold value. CONSTITUTION:A detection signal 9a obtained by converting the intensity of reflected light or scattered light 6b generated by an object 1 to be inspected which is irradiated with an S polarized laser 6 into an electric signal by means of an optoelectric transducer 9 is compared with a threshold value TH; by this setup, a foreign body which has adhered to the object 1 to be inspected is inspected. The following are installed: a frequency-analyzing part 14 to detect a frequency distribution of the detection signal 9a corresponding to the intensity of the reflected light or the scattered light 6b over a whole area of the object 1 to be inspected; a threshold-value computing part 15 which sets the threshold value TH automatically on the basis of this frequency distribution. It is possible to accurately discriminate between the reflected light or the scattered light 6b from a substratum and the reflected light or the scattered light 6b from the foreign body to be inspected or the like by referring to the optimum threshold value TH in accordance with a surface state or the like of the object 1 to be inspected.

Inventors

• 👤 Yoshikazu Tanabe

Bibliographic Details