SURFACE INSPECTION METHOD FOR FRP PRODUCT

摘要

PURPOSE:To allow the well conduction of the surface inspection of an FRP product by Fresnel diffraction by adjusting the distance between a spot light source and an inspection surface and maximizing the S/N of an ordinary surface pattern and the pattern of a true defect. CONSTITUTION:Rays of the light source 1, such as ultra-high pressure mercury lamp, are imaged at a focus by a lens system 2 to form the spot light source 3. The surface 4 of the FRP product is irradiated with the ray thereof and the annular pattern is generated on a screen 5 by the Fresnel diffraction of the reflected light. The difference between the patterns is made distinct if the S/N of the annular pattern occurring in the undulation of the ordinary surface and the annular pattern occurring in the product defect is maximized by adjusting the distance (a) between the spot light source 3 and the inspection surface 4. A recessed part P is thus easily detected. The contrast is maximized near the distance a=50mm in this case.