A method for measuring the guideway straightness error based on polarized interference principle

This paper presents a new method for measuring guideway straightness error based on the polarized interference principle and affords a new way to measure straightness error in real-time with high precision. Firstly, the method is demonstrated and analyzed in theory, and then the layout of the optical modulator and the polarization angle detecting unit are discussed in details. Finally, a calibration process is introduced with linear function based on the least-square method. Calibration results show that the correlation coefficients R2 of the fitting curves are above 0.9999 and the standard error of the estimated value is less than 0.2 μm. The theoretical analysis of the relationship between the straightness error and polarization angle is verified. The range of measuring straightness error is above 0.5 mm with 0.5 μm resolution. The system uncertainty (k=3) is less than 1 μm after the measurement system is calibrated. Experimental results demonstrate that this method possesses the advantages of minimizing the effects caused by the variation of light intensity and the shape and surface error of the guideway. The measurement accuracy is considerable with the autocollimator having the characteristic of high reliability and accuracy. It will have a prospective application in the industrial measurement field.