| 摘要 |
A sensor arm (1) is inserted into a hole (3). The arm is mounted on a pivot (5) perpendicular to the arm axis so that it may be urged into engagement with the wall of the hole, e.g. by an air cylinder (12). The pivot (5) is in turn rotated about an axis passing through the hole, preferably by means of a rotary body (10). A bearing piece (16) controlling the sensor arm may be moved towards or away from the hole and rigidly supports a light sensor (8) that receives a light beam (7) from the sensor arm. The geometry of the hole is determined on the basis of the position where the light beam impinges on the sensor and the position of the bearing piece relative to the hole. |
