A New Method for Circular Grating´s Eccentricity Identification and Error Compensation

The eccentricity is the main concern when installing a benchmark circular grating, because it accounts for the majority of the angular measurement error. A new method to identify the magnitude and direction of the eccentricity after the installation was proposed. Compared with models in the form of Fourier series, the model of the new method has fewer coefficients and a better error compensation effect. According to the calibration experiment, putting the new model into practical error compensation, the uncertainty of the angular measurement was reduced by 79.4%.