A Novel Baseline Measuring System Based on Femtosecond Comb Laser and High-Resolution Camera

Precise baseline measurement plays an essential role in interferometric SAR (InSAR) mission. In order to obtain high-accuracy of land elevation, baseline measurement system with high precision is currently required at large inter-antenna distance. In recent years, baseline estimation method and GPS-based measurement system have made some progress in practical applications. However, such two measurement schemes are highly dependent on massive ground post-processing techniques, which prevent from real-time implementation. As a promising alternative, laser and camera measurement system has drawn widespread attention for InSAR utilization nowadays. In this paper, by incorporating a femtosecond comb laser into the laser-camera system, we propose a novel framework for baseline measurement, which could realize high-accuracy observation in real time. After calibrating the laser and camera compartments simultaneously, we validate the performance of the proposed system using a laser tracker as a reference equipment on a hyper-stable platform. The experimental results have shown that the errors of position and attitude are less than 0.2 mm and 15 arcseconds at 60 m distance respectively, which have demonstrated the sub-millimeter precision, long-range and high-speed capabilities of our system.