INSPECTION DEVICE FOR DEFECT INSPECTION

The present invention comprises an inspection method for transparent or reflective inspection objects, by using a retro-reflective plate as a convex lens or concave mirror in such a way that defects can be detected in a stable fashion even if the inspection object is curved or if vibration occurs during movement of the inspection object; in which displacement of parallel light passing through or reflected in a measurement field is captured by using changes which occur in an inspection field, namely changes in the density gradient in the case of transmission inspection or in the reflection angle in the case of reflection inspection. The present invention also comprises an inspection device for defect inspection, in which a knife edge is provided, horizontally to the optical axis, on the front surface of a camera lens for collecting the transmitted light or reflected light, in such a way that three-dimensional defect images can be obtained since any light which diverges from the parallel light is blocked with consequent changes in the contrast of the light due to the density gradient in the inspection field at the camera.