A fast steering mirror with ultra-low geometric tilt-to-length coupling noise for space-borne gravitational wave detection

Abstract

The misalignment between the geometric center and rotation center in fast steering mirrors (FSMs) poses a challenge for space-borne gravitational wave detection, as it results in geometric tilt-to-length (TTL) coupling noise. To address this issue, we have proposed a FSM structure that exhibits ultra-low geometric TTL coupling noise. The geometric TTL coupling noise is analyzed and evaluated strictly considering the FSM non-ideal tilt of the plane and the center shift characteristic of cartwheel flexure hinges under a small rotational angle. Compared to traditional FSM designs, our new design offers superior noise suppression capabilities and is capable of meeting the stringent piston effect noise requirements of 0.2 in the frequency band of under ideal conditions.