The STELLA Echelle Spectrograph (SES). (a) top: The instrument is mounted on a Newport optical bench on four gas-damped legs on a pier separated from the building. The table and its optical and mechanical components are enclosed with a dust cover made of anodized aluminium sheets (partly removed in this picture). This cover together with the bench legs is additionally enclosed in a thermal insulation chamber (also partly removed). This chamber is in a dedicated room with active temperature control. (a) bottom: The heart of the spectrograph, the R2 31-l/mm echelle grating (covered). (b) Overview of the opto-mechanical design and its components.