| 摘要 |
PURPOSE:To uses the full stroke of a fast moving base for measurement and to perform the measurement efficiently by correcting an error caused by variation in the moving speed of the fast moving base according to the measurement result of a relative optical path length difference or relative optical length difference varying speed. CONSTITUTION:The relative optical path length difference and relative optical path length difference varying speed are measured by a differentiator 31 and a differential transformer 30, an oscilloscope is swept corresponding to the measured relative optical pat length difference, and the cutoff frequency at the time of the separation of fast vibration components is varied by an AM modulator 35 corresponding to the relative optical path length difference varying speed. At the same time, the relative optical path length difference is measured and every time the relative optical path length difference is varied by a constant quantity, the differentiator 31 outputs a voltage pulse, so that the fast vibration component and a direct nearby component are separated and displayed in synchronism with a voltage pulse train generated as mentioned above. |
