Space-based distributed array telescope formations, through multi-telescope collaborative observation and long-baseline optical interferometry, can significantly enhance deep space exploration capabilities, providing key technological support for missions such as asteroid monitoring and the search for extraterrestrial life. However, the measurement and control performance of such formations is highly dependent on the precision of intertelescope baseline measurements. Frequency-sweeping interferometry (FSI) technology, with its significant advantages—including freedom from the ambiguity range limitation, capability for non-cooperative target measurement, strong anti-interference ability in complex space environments, and high maturity of core components—has emerged as the most promising technical approach for baseline measurement in space-based distributed array telescope formations. Nevertheless, advancing this technology toward aerospace engineering applications still faces two major challenges: suppressing optical frequency-sweep nonlinearity and eliminating dynamic ranging errors. Currently, using electro-optic modulation to generate highly linear, synchronized, symmetrically sweeping positive and negative sidebands—establishing a frequency-sweeping interferometry system based on electro-optic sideband modulation—represents an effective method to address the issues of sweep nonlinearity and Doppler dynamic error. However, frequency-sweeping interferometry systems based on electro-optic sideband modulation lack a traceable on-orbit optical frequency-sweep reference, making it difficult to ensure long-term stable measurement and accuracy maintenance on orbit. Therefore, further research into high-precision electro-optic sideband modulation-based frequency-sweeping interferometry methods with traceable sweep references is of great significance for advancing the development of baseline measurement technology for space-based distributed array telescope formations.
Recently, in a research article published in Space: Science & Technology, Academician Weimin Bao's team at Xidian University proposed a double-sideband frequency-sweeping interferometry (DSB-FSI) technique based on Fabry–Pérot (F-P) etalon calibration. The study established an intersatellite baseline measurement architecture comprising an electro-optic modulation-based double-sideband frequency-swept laser source module, an F-P etalon-based optical frequency-sweep rate calibration module, and an optical hybrid quadrature detection module. By acquiring beat signals generated by the symmetrically sweeping sidebands through quadrature detection, the Doppler error in dynamic ranging is eliminated. Online calibration of the optical frequency-sweep rate is achieved based on the time-domain intervals of the F-P etalon's resonance peaks. Experimental results demonstrate that the ranging system reduces measurement drift error from 20.11 μm to 13.38 μm over a 5.7 m baseline, improving stability by 33.47%. The ranging accuracy reaches 44.30 μm over a 10 m range. Within a velocity range of 5–20 mm/s, the system exhibits a displacement measurement linearity better than 0.99999, a velocity measurement deviation of less than −16.80 μm/s, and a vibration measurement error of less than 0.08 μm. This study provides a feasible technical solution for high-precision and stable intersatellite baseline measurement in the "MEAYIN" project.
