Frequency-Sweeping Interferometry for Intersatellite Baseline Metrology in Array Telescope Formation

Space-based distributed array telescope formations hold substantial potential for deep space exploration, with their performance highly dependent on precise baseline measurements between subtelescopes. This study presents a double-sideband frequency-sweeping interferometry (DSB-FSI) technique based on electro-optic modulation for intertelescope baseline measurements. To address the lack of on-orbit frequency-sweep calibration references, a Fabry–Pérot etalon is used for real-time in situ frequency-sweep rate calibration. Experimental results show that the Fabry–Pérot etalon effectively calibrates the frequency-sweep rate of the DSB-FSI system, reducing long-term baseline measurement drift error from 20.11 to 13.38 μm and decreasing maximum measurement deviation from 18.03 to 13.14 μm over a 5.7-m baseline. Metrological calibration confirms that the calibrated system achieves a baseline measurement accuracy of 44.30 μm over a 10-m range, with excellent dynamic measurement performance for monitoring baseline variations. The DSB-FSI technique is expected to provide a reliable solution for the high-precision intertelescope baseline measurements in “MEAYIN” (Multiple-Spacecraft Exoplanet Aperture Synthetic Interferometer) project, thus supporting the advancement of space-based distributed array telescope formation technologies.