Plane mirror interferometer is a common way for the precision displacement measurement. However, during the measurement, it still suffers from disturbances such as misalignments, rotations and air refractive index fluctuations, which lead to poor accuracy. Traditional error analysis is rather limited in the static state and separation of the disturbances. In this paper, displacement measurement errors are analyzed, which are caused by the disturbed factors for a plane mirror interferometer. Then error modeling, which based on the geometric optical paths, is carried out by the partial differentiation theory. Moreover, the characteristics of the error are discussed by using this model. It is suggested that this model can release the measurement accuracy reduction brought by coupling effects between adjustment factor of the optical paths and the rotary error of the measured object (e. g. a guideway).

Collinear calibration is a typical and common method for a laser (heterodyne) interferometer, but it usually suffers from the influence of the tilt of the target retroreflectors and the dissymmetry of the optical paths during the calibration. This paper mainly analyzes and models the calibration error caused by the tilt error of the target retroreflectors and reveals the error source that is the disturbance from the rotary error of the guideway slider pair. Experimental results prove the validity of the analysis and model of the calibration error. The calibration error is up to 0.5 μm when the tilt error is 0.36°, which is large enough to equal the maximum tolerance of laser interferometer (0.5 μm) in use.

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