Design and Implementation of an Improved Optical Bench for Inter-Satellite Laser Interferometry

Abstract

This thesis presents a redundant laser (de)coupling scheme for future inter-satellite interferometry missions, like successor missions to GRACE-C and NGGM, that has virtually no power loss with minimal additional optical components compared to already utilized optical benches. This was achieved with a diagonal linear polarization. It was found that with the used optical components some unforeseen polarization changes happened at the mirrors and beamsplitters. Both were attributed to the usage of off the shelf components and are expected to be minimized with either laser line mirrors or specifically for diagonal polarization manufactured components. At the reflection on the mirrors a high degree of circular polarization was generated which is not expected to be an issue because p- and s- polarization are separated before the detection anyway. The recombination beamsplitter is identified to be a larger issue because it rotates the polarization which leads to an unequal power distribution at the QPDs. Altogether the functionality of the proposed optical bench was proven theoretically and in the laboratory and in the end a modification of the optical bench was tested which resolved the polarization issues.