| 摘要 |
In order to increase the measurement accuracy in the case of determining the offset of an object from a reference line which is defined by an optical measuring device, a rotatable shutter (12) is arranged in the imaging plane of the objective (11) of said measuring device. The shutter (12) has an opening (21) which is bounded on one side by a straight line and by a logarithmic spiral on the other side. The radiation pulses which strike a photosensor (15) during rotation of this shutter have a different length, depending on the distance of the image in the imaging plane from the centre, and have a different phase angle with respect to the shutter rotation, depending on the angular position of said image. The position coordinates of the imaged target object with respect to the reference line can be determined by means of evaluation electronics (17) in this manner, the measurement accuracy being linear with respect to the distance of the image from the centre of the shutter, that is to say being small close to the centre. <IMAGE> |
