PATTERN INSPECTING APPARATUS

摘要

PURPOSE:To simplify mechanism and speed inspection by using a filter having a light transmission region. CONSTITUTION:A filter 17 having a ring-form light transmission region is disposed on the rear focal plane of an imaging lens 16. As a result of this, the light from a coherent light source 11 transmits through the subject 15 which is rotated by a rotating mechanism 22, after which it forms the Fourier transformation image of the subject 15 on the rear focal plane of the imaging lens 16 and only the light component by the defect of the subject 15 passes through the filter 17 and images as a light spot in correspondence to the position of said defect on the imaging plane 18. Thence, it passes through a pinhole 19 and is converted to the electric signal corresponding to the size of the defect by a photoelectric transducer 20. This signal causes an incoherent light source 14 to light up. Hence, the position and size of the defect of the subject 15 are displayed in a monitor 29 by way of a dichroic mirror 27 and ITV camera 28.