Subtraction of test mass angular noise in the LISA Technology Package interferometer

TL;DR

This paper demonstrates that angular noise in the LISA Technology Package interferometer can be effectively subtracted, ensuring the required displacement resolution for gravitational wave detection without limitations from test mass jitter.

Contribution

The study shows successful subtraction of angular noise from displacement measurements, improving the interferometer's sensitivity for space-based gravitational wave detection.

Findings

Achieved 9 pm/√Hz displacement resolution above 3 mHz

Successfully subtracted angular noise contribution from test mass jitter

Confirmed no limitation from cross-coupling to the interferometer's performance

Abstract

We present recent sensitivity measurements of the LISA Technology Package interferometer with articulated mirrors as test masses, actuated by piezo-electric transducers. The required longitudinal displacement resolution of 9 pm/sqrt[Hz] above 3 mHz has been demonstrated with an angular noise that corresponds to the expected in on-orbit operation. The excess noise contribution of this test mass jitter onto the sensitive displacement readout was completely subtracted by fitting the angular interferometric data streams to the longitudinal displacement measurement. Thus, this cross-coupling constitutes no limitation to the required performance of the LISA Technology Package interferometry.