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Publication Details
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| Citation: | Zili Zhang1,2, Dabao Lao1,2, Dengfeng Dong1,2, Rongyi Ji1, Weihu Zhou1,2* (1, Academy of Opto-Electronics, Chinese Academy of Science, No. 9 Dengzhuang South Road, Beijing, China; 2, University of Chinese Academy of Sciences, No.19 Yuquan Road, Beijing, |
Abstract
Laser tracking measurement system is one of the most commonly used large-scale measurement systems in the fields of aircraft inspection, ship-building, automobile assembly and other machinery manufacturing. It can get an object’s spatial position using combination of distance measurement and angle measurement. Traditional laser trackers use interferometer or phase ranging to realize distance measurement whereas each technology has its own strengths and weaknesses. Interferometer can realize high-accuracy and high-frequency distance measurement whereas it can only determine relative distances. Phase ranging can implement absolute distance measurement, however its measuring frequency is limited due to its measuring principle. In this paper a novel laser tracking measurement system was presented which realized high-frequency absolute distance measurement using dual femtosecond optical frequency comb with the accuracy of 0.5ppm. Firstly the measuring principle and overall design of the system were introduced. Then the components of the instrument were analyzed including laser source module using femtosecond laser frequency comb, distance measurement module combing dual-comb distance measurement with phase distance measurement, angular measurement module using circular grating, tracking and control module based on DSP and FPGA, geometrical error calibration and error compensation module and data processing software. The measuring principle of each module was detailed as well as the configuration. Finally a prototype of the measurement system was established. The test results showed that the distance measuring accuracy is better than 0.5ppm and the angle measurement errors were compensated to less than 1″. The tracking control module can track a moving optical target with speed of 2m/s. Comprehensive error calibration and compensation were carried out and the overall coordinate measurement accuracy is testified to be better than 10 ppm. Also preliminary attitude measurement installation combing the laser tracker with a single camera is set up to realize 6-DOF measurement. More intensive studies and experiments were expected to do to enhance the accuracy, stability of the system and to extend the functions. Laser tracking measurement system as well as distance measurement device based on femtosecond optical frequency comb are expected to have broad application prospect in large-volume measurement fields.
