Properties of an optical phase-shifter made of two gold mirrors

Reflectivity and phase-shift properties of a device composed of two flat mirrors with a gold coating 1 μm thick have been measured, at some relevant light incidence angles, for λ1=488nm and λ2=514.5nm. An experimental investigation of the low-frequency noise (around 50 mHz) contributed by the phase-shifter in an ellipsometer is described.