Laser tracker system (LTS) is one of the latest portable three dimensional large size coordinate measuring machines (CMMs). It can measure moving object 3D coordinates using the technology of laser interferometer length measurement

precision angle measurement and target tracking. However

its measuring accuracy is profoundly affected by the target retro-reflector receivable angle

in order to resolve the problem that LTS can not continuously measure corner cube retro-reflector (CCR) position in dynamic conditions restricted by CCR’s receivable angle; we have developed an angular automatic calibration mechanism for LTS to measuring the CCR positions in real time. The calibration mechanism mainly includes precision circular guide-way and angular automatic adjustment device

which can make the CCR always tracking the laser beam emitted from LTS all the time. The designed calibration mechanism and Hexagon Globle9128 coordinate measuring machine are used to compensate the angular measuring error of LTS. The experimental results demonstrate that the maximum angular measuring error of LTS in measuring distance of 0.752m has been decreased sharply from 34.69m to 9.71m in horizontal direction and 35.43m to 10.03m in vertical direction. Therefore

the LTS angular measuring accuracy is effectively improved.