In this thesis we present two distinct interferometric set-ups for displacement measuring interferometry in cryogenic Low Energy Electron Microscopy (LEEM), specifically for use in ESCHER, the LEEM...Show moreIn this thesis we present two distinct interferometric set-ups for displacement measuring interferometry in cryogenic Low Energy Electron Microscopy (LEEM), specifically for use in ESCHER, the LEEM at Leiden University. The set-ups are based on: 1. circular polarization and 2. 3x3 fiber couplers to obtain a quadrature measurement. Whilst the 3x3 coupler based set-up is limited by thermal drift and other environmental effects, the circular polarization based method displays a 3\sigma resolution of 1.75 nm, and we provide a framework for further increasing this resolution, including a set of alternate set-ups with slight added complexity but a great potential gain in resolution. Keywords: Displacement, Interferometry, Fiber Couplers, Polarization, LEEM, cryogenic, DMI, Quadrature, Fiber.Show less