Abstract: A workpiece surface is measured to detect a defective portion with a projection and a depression on the workpiece surface by using an optical inspecting apparatus having a projector for radiating a detecting light towards the workpiece surface and a picturing device for receiving a reflected light from the workpiece surface. A reflected light from the workpiece surface is pictured in a condition in which a focal surface of the picturing device is positioned away from the workpiece surface to the side of the picturing device relative to an entire region of that effective inspecting range of the workpiece surface from which the picturing device can receive the reflected light. The defective portion on the workpiece surface is detected from a dark portion which appears on the image of the picturing device.

Abstract: A method of inspecting a curved surface of a workpiece by a surface inspecting apparatus provided with a projecting device for illuminating the workpiece surface to be inspected with detection light, a detecting device for receiving and detecting the light reflected from the workpiece surface, and a condensing optical system for causing the reflected light to converge on a light-receiving surface of the detecting device. According to the method, the surface inspecting apparatus is successively displaced along the workpiece surface and the reflected light is detected by the detecting device. Further, image data obtained from the detecting device is held and binary digitized. It is determined whether or not the workpiece surface to be inspected is planar. If it is not planar, then the digitized image data is processed for dilation and erosion. Thus, when the workpiece surface is curved, faulty or defective spots can be reliably detected.