Three-axis vibration measurement of the linear air-bearing stage demonstrated by utilizing the method of the multi-axis laser interferometer is discussed. In order to detect the X-Y-Z directional vibration of the positioning stage table simultaneously, two-dimensional XY gratings are utilized as the scale grating and the reference grating of the interferometer. The X- and Y-directional positive and negative first-order diffracted beams are superimposed to generate the interference signals on the photodetectors. When the multi-axis vibration is applied to the scale grating, the intensities of the interference signals in X- and Y-directions varied corresponding to the vibration of the scale grating. Consequently, three-axis vibrations of the scale grating can be calculated by processing the X- and Y-directional positive and negative first-order interference signals. In this paper, a three-axis vibrometer based on the grating-interferometer has been developed for measurement of the positioning stage table vibration. The detection method of the vibration based on the Doppler frequency shift has been demonstrated. As an application of the multi-axis grating-interferometric vibrometer, multi-axis vibrations of the linear air-bearing stage are measured by using the developed vibrometer.
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