A hexagonal quasi-monolithic optical bench has been built to demonstrate critical technologies in LISA on the ground.

This setup generates three optical beat notes pairwise from three beam sources phase-locked to each other and conceptually acts as a miniature scale LISA. With this ultra-stable testbed, essential devices like phasemeters and photoreceivers can be tested at required pico-meter precisions [1]. Furthermore, the experiment is used to test elements of the LISA data analysis pipeline such as Kalman filtering, time-delay interferometry ranging, interpolation, and others.

The latest demonstration of clock synchronization with this setup reached nano-second accuracy and verified specific noise coupling mechanisms, e.g. interpolation errors and aliasing effects, stemming from LISA data analysis [2]. To incorporate ranging into this experiment, we are currently finalizing the design of the so-called delay-locked loop on our phasemeter.

Finally, due to the central role the Hexagon plays in testing core technology for LISA, an improved second version of the Hexagon has been designed and is now ready to be constructed, not only for redundancy purposes but also to be able to run two test campaigns in parallel.


Schwarze, T. S.; Fernández Barranco, G.; Penkert, D.; Kaufer, M.; Gerberding, O.; Heinzel, G.: Picometer-Stable Hexagonal Optical Bench to Verify LISA Phase Extraction Linearity and Precision. Physical Review Letters 122 (8), 081104 (2019)
Yamamoto, K.; Vorndamme, C.; Hartwig, O.; Staab, M.; Schwarze, T.; Heinzel, G.: Experimental verification of intersatellite clock synchronization at LISA performance levels. Physical Review D 105 (4), 042009 (2022)

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