When the four-quadrant detector is detected using the pyramidal prism to reflect the light, the dihedral angle error causes the spot offset. In this paper, the relationship between the reflection spot offset and the three dihedral angle errors is analyzed by combining the pyramid model with the detector detection principle, and the influence of the dihedral angle error on the center shift of the reflected light spot is explored qualitatively and quantitatively. The simulation results show a high degree of central symmetry, which can be used to eliminate the system error resulting from the dihedral angle error of the corner prism, in order to minimize detection accuracy to 0.1μm. In addition, The simulation results provide a theoretical basis for the subsequent coaxial accuracy test.
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