| 摘要 |
PURPOSE:To measure a fine angle of rotation easily and precisely by arranging a substrate where elements A are arrayed at equally (n)-divided positions on the circumference coaxially with a rotating disk where elements B are arrayed at equally (n+m)- divided positions of the circumference of nearly the same diameter, and measuring the relative angle of rotation between the substrate and rotating disk from a shift in the phase of array-order variation in the amount of information occurring to the element A or B. CONSTITUTION:When the rotating disk 20 is irradiated with uniform light from above its top surface side, respective sensors 11 on the substrate 10 photodetect the light through small holes 21 of the rotating disk 20 and their outputs vary in array order as shown by black dots. Namely, the array-order variation of outputs of the photosensors 11 of the substrate 10 shows a two-cycle wave having two maximum and minimum values each. Then, when the rotating disk 20 is rotated slightly, each photosensor varies in the amount of photodetection and the wave shifts in phase as shown by white round marks. Namely, the slight rotation of the rotating disk 20 causes the wave of array- order variation of the photosensors to shift in phase greatly. The outputs of the photosensors 11 are processed statistically to reduce an error of the calculated value of the phase based upon a mechanical error. |
