| 摘要 |
A device for automatic magnetic powder testing of test samples (2) on which a ferromagnetic powder is applied after magnetization. If fissures are present, the powder will cumulate around the edges of said fissures. The device comprises a light source (16) having a light path (12) directed towards the sample, thereby producing a light spot on its surface, which light spot is moved in accordance with a scanning procedure. A light-detection unit (18) picks up the light which is reflected when the light spot strikes the surface of the sample. This reflected light follows the same path as the ray of light towards the sample. A light-reflecting element (14) is provided with a light opening (15) which, by adaptation of its size, lets through concentrated light which is reflected directly from the surface of the sample, whereas light which is generated due to the fact that the ray of light incides upon an accumulation of magnetic powder is spread outside the light opening and reaches the light-detection device due to deflection by means of the reflecting element. |
