Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 44: Laser Technology and Applications

Q 44.5: Vortrag

Donnerstag, 5. März 2026, 12:00–12:15, P 2

On-axis Laser Ranging Interferometer for Grace-like Mission — •Daikang Wei — Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Hannover, Germany

The GRACE Follow-On mission’s laser ranging interferometer (LRI) has demonstrated sub-nanometer precision for inter-satellite length tracking. We present a novel interferometric architecture for future GRACE-like missions, featuring an on-axis LRI that enables monoaxial transmission and reception of laser beams between two spacecraft. Our laboratory-scale prototype establishes a transponder-based laser interferometric link between two optical benches, with phase readout at a heterodyne signal of 7.3 MHz. Two independent active beam steering loops employ differential wavefront sensing (DWS) to co-align the transmitting (TX) and receiving (RX) beams. Under simulated angular jitters, the beam pointing stability is maintained below 10 µrad/√Hz in the frequency range between 2 mHz and 0.5 Hz, and the fluctuation of the TX beam’s polarization state induces a reduction of 0.14% in the carrier-to-noise-density ratio. Additionally, we investigate the tilt-to-length (TTL) coupling of the optical bench using dedicated rotations of the hexapod. Our results show that the on-axis LRI enables inter-spacecraft ranging measurements with nanometer accuracy, making it a potential candidate for future GRACE-like missions.

Keywords: Laser interferometry; GRACE; Differential wavefront sensing; Inter-satellite ranging; Heterodyne readout