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Error analysis of 2-D diffraction grating interferometer for high-resolution displacement measurement

2-D grating interferometer configuration for high resolution displacement measurements is introduced, and the interferometer uses one cross grating as the scale to achieve planar displacement measurement. According to 2-D grating interferometer structure, error sources are analyzed, and the pitch and yaw of 2-D grating guide caused by planar guide's non-linearity is the main factors to decrease the measurement system's accuracy. The theoretical analysis of the three spatial axes guide error is carried out and the related errors are evaluated separately. According to the analysis, the measurement accuracy is sensitive to 2-D grating movement's pitch and yaw, the grating's location deflections are only systematic error and can be compensated by calibration experiments and software, some methods of system error correction and system mount are given. In order to decrease the system sensitivity to the errors of the grating plane movement, the improved configuration is proposed.