On-axis Optical Bench for Laser Ranging Instruments in future gravity missions

TL;DR

This paper presents a design for an on-axis optical bench for future gravity mission laser ranging, improving optical power and beam divergence to enable longer interferometer arms and better thermal robustness.

Contribution

It introduces a novel optical bench design that enhances received power and beam divergence, verified through simulations and thermal analysis for space applications.

Findings

Design improves optical power reception

Enables longer interferometer arms

Shows robustness to orbital temperature fluctuations

Abstract

The Laser Ranging Interferometer onboard the Gravity Recovery and Climate Experiment Follow-On mission proved the feasibility of an interferometric sensor for inter-satellite length tracking with sub-nanometer precision, establishing an important milestone for space laser interferometry and the general expectation that future gravity missions will employ heterodyne laser interferometry for satellite-to-satellite ranging. In this paper we present the design of an on-axis optical bench for next-generation laser ranging which enhances the received optical power and the transmit beam divergence, enabling longer interferometer arms and relaxing the optical power requirement of the laser assembly. All design functionalities and requirements are verified by means of computer simulations. A thermal analysis is carried out to investigate the robustness of the proposed optical bench to the temperature fluctuations found in orbit.