This thesis opens with a brief review of the aspects of gravitational waves which are relevant for detector design and engineering, and an introduction to the LISA and LISA Pathfinder missions. The thesis describes original work carried out to support the LISA Pathfinder mission at the University of Birmingham. The salient space mission quality requirements and mission specific technical and documentation requirements are set out. The classical and computer based mechanical analysis, birefringence optical inspections, and linear elastic fracture mechanics and fracture control engineering which were applied to support flight acceptance of the brittle glass-ceramic optical bench interferometer structure are presented. The design of a new photodiode mount is shown and justified, while the mechanical, optical, and electrical analysis, electrical and optical testing and, finally, the installation and alignment of the photodiodes are presented.