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A calibration method of capacitive displacement sensor based on laser interference

In order to meet the requirement of frequent in-situ calibration before micro-thrust measurement, a new calibration method based on laser interference is proposed. Based on common optical elements, the interference light path is set up, and the light path adjustment process is simplified by using the visible light of 532nm wavelength as the light source. The calibration principle is that the capacitive displacement sensor and laser interferometer simultaneously measure the movable pyramid prism’s position change resulted by adjusting displacement table, and the measurement result of laser interferometer is viewed as the reference displacement to carry on the sensor's calibration. By comparing with the sensor output, the method of calculating the number of fringes corresponding to optical path difference is analyzed. The practicability and accuracy of the calibration device is verified by experiment, and the calibration results and the relative error are analyzed at last.