| 摘要 |
PURPOSE:To enable accurate measurement of all types of displacement by separating the changes in the optical path length of Fabry-Perot interferometer into AC components and DC components, and changing the position of the interferometer's mirror to cancel out variances in the components and any deviations. CONSTITUTION:When the object of measurement is accelerated weight 2 vibrates and the AC components and DC components are included in the interferometer signal. The AC component of the signal is passed through high-pass filter 22, and voltage displacement device 5 is driven by the output signal from integrated amplifier 23, and the signal is inverted by the this amplifier. This causes a drive signal that cancels the movement of weight 2 to be supplied to voltage displacement device 5 in accordance with the interferometer signal. Thus, displacement means 5 always maintains its distance to remain in line with the midpoint of the interferometer, and only distance l changes relative to external vibration. The piezoelectric displacement means can measure displacement lby detecting the voltage of terminal 26 since there is a linear relationship l=alphaV (alpha is a proportional constant) between signal voltage V applied by amplifier 23 and displacement 1. |
