Calibration the tracker’s angle measurement error for LINAC control network

LINAC control network is the reference for optical axis transmission. According to the layout of key equipment in LINAC tunnel, the control network is laid out on the ground and wall of the tunnel. Tracker is the main instrument for measuring LINAC control network, and the angle measurement error is a key factor affecting the accuracy of the tracker. Based on the layout of wall and ground network points and the measurement plan, laser tracker’s angles were decomposed horizontal and vertical angles in all measurement states. Then, through the linkage testing of high-precision CMM and laser trackers, all the decomposed angles were calculated, and the calculated values are used to correct the tracker’s measurement angles. Based on the test results, regardless of the measurement state, measured angle of the tracker is larger than the calculated value. The ground network points’ vertical angle deviation and horizontal angle deviation almost equal to the nominal accuracy of the tracker. When the horizontal angle of wall points exceeds 15 degree, deviation increase significantly, and the deviation should be corrected while measuring the wall network points.