Figure 7
From: Ultra-stable clock laser system development towards space applications
(left) Cut through the vacuum system containing the ultra-high finesse optical cavity used to stabilise the clock laser.
The spacer of the cavity is made from Ultra Low Expansion (ULE) glass to which fused silica mirrors with thermal compensation rings are optically contacted. The cavity is mounted on three titanium legs and surrounded by two gold plated aluminium shields and the gold plated aluminium vacuum chamber. The outer heat shield is connected to a temperature-stabilised copper thermal feedthrough, which is temperature stabilised with a thermoelectric cooler. The vacuum chamber is pumped by a 2 l/s ion pump and a non-evaporable getter. Laser beam is coupled from the top and the transmitted signal leaves the cavity through the bottom viewport. (center) Details of the mounting of the cavity with view on the inner heat shield. (right) Detailed cut of the mounting of the cavity and the inner heat shield to the titanium legs.
