摘要 |
A measuring apparatus comprises a sensor having a vibrating beam whose resonant frequency represents a parameter, such as pressure, to be measured. A light guide supplies light from a source to the beam and returns light reflected from the beam and from the end of the guide to an interferometer. The difference in light paths is greater than the coherent length of the light. The interferometer has first and second paths which differ in length by the difference in the light paths plus an odd number of quarter wavelengths of the light.
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