High precision stability measurement of large size structure using dual femtosecond frequency combs ranging system

To achieve the high precision absolute distance measurement of large aperture remote sensor structure, a large range and high precision distance measuring method based on the dual optical frequency combs was presented. Two femtosecond combs with repetition frequency locked were used in the system, and the repetition frequency difference between combs had great influence on ranging accuracy. To measure the stability of the remote sensor structure, the Michelson interferometer optical structures have been launched. The experiment results demonstrated that the system was capable of large range and high accuracy distance measurement. For a continuous measurement of 2.6m distance, the ranging accuracy was 5×10^-7. The system has applied in stability measurement of a 1.8m length main structure, and the test result has demonstrated the structure stability was less than 2μm.