Design and Error Compensation Technology of Dual Frequency Length Measurement System for Space Applications

This paper proposes a miniaturized and lightweight dual frequency laser interferometry measurement system to improve the ground observation accuracy of dual antenna interferometric spaceborne synthetic aperture radar as well as to achieve ultra-high precision radar baseline measurement. The error model for the measurement system is then established. The impact mechanism of numerous faults thereafter is studied, and the phase drift error induced by changes in signal amplitude is identified as the primary system defect. To mitigate the impact of the mistake used for real-time compensation, a phase-amplitude detection circuit was created by combining digital phase measurement methods. Finally, the ranging performance of the system is experimentally verified. The results show that the dual-frequency laser interferometric measurement system has a volume of 120 mm x 20 mm x 80 mm, meeting the requirements of miniaturization and lightweight design. The relative displacement resolution at 10 meters can reach 0.1 µm, and the peak displacement measurement error is better than 0.2 µm.