| 摘要 |
Precision displacement and load measurements dependent upon the intensity or attenuation of a signal, as by use of Moire fringe gratings or photoelastic load cells, are made using speed-of-light ranging techniques based on heterodyne frequency conversion with multiple phase-locking. Coiled optical fibres introduce phase delays in radio-frequency-modulated laser rays which are then compounded in phase by selective signal attenuation and merger. The phase is then measured by high precision circuits involving ceramic filters and translated into position or load data. Machine tool control and strain gauge applications are described. The ceramic filter circuit generates a signal measuring rate of change of displacement as a by-product, thereby facilitating measurements involving rapid motion.
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