| 摘要 |
A light source, preferably an electrical flash tube, generates a beam of light which, preferably, is collimated to provide a parallel beam output. The workpieces are placed in the beam of light to generate a shadow image. The shadow image and surrounding beam portions are projected on a screen, with intervening optical enlargement, on which photoelectric sensors are located positioned in the projected shadow image and preferably also in adjacent regions of the light beam, the outputs from the sensors being compared with each other, or with a reference, to determine relative shadow image characteristics of regions of the objects in the light beam path, the output signals being a measure of differences in characteristics, and hence determinative of orientation, size, or integrity of the workpiece material. To test for size or orientation, two sensors are located at the end portions of the shadow images of pins, or bolts, carried through a test path interposed between the parallel beams from the light source, before enlargement. |
