Compact Laser Collimation System for Simultaneous Measurement of Five-Degree-of-Freedom Motion Errors

A compact laser collimation system is presented for the simultaneous measurement of five-degree-of-freedom motion errors. The optical configuration of the proposed system is designed, and the principle of the measurement of five-degree-of-freedom errors is described in detail. The resolution of the roll and the horizontal straightness is doubled compared with other laser collimation methods. A common optical path compensation method is provided to detect light drift in real time and compensate for straightness and angle errors. An experimental setup is constructed, and a series of experiments are performed to verify the feasibility and stability of the system. Compared with commercial instruments, the pitch and yaw residuals are +/- 2.5 '' and +/- 3.5 '' without correction, and the residuals are +/- 1.9 '' and +/- 2.8 '' after correction, respectively. The comparison deviations of the horizontal straightness and vertical straightness changed from +/- 4.8 mu m to +/- 2.8 mu m and +/- 5.9 mu m to +/- 3.6 mu m, respectively. The comparison deviation of the roll is +/- 4.3 ''. The experimental results show that the data of the five-degree-of-freedom measurement system obtained are largely the same as the measurement data of commercial instruments. The common optical path compensation can effectively improve the measurement accuracy of the system.