(ed.). Gravitational waves (IOP, 2001)(422s).

Description of the LISA mission 119Figure 10.4. Mounting of optical assemblies inside main thermal shield. Each opticalassembly must rotate slowly and smoothly during the year over about a one degree range.Figure 10.5. Optical bench for one optical assembly. Light from the laser is mainly sentout to the telescope, with a little going to the photodiode. Received light from the other endof the arm passes through the beamsplitter to the test mass, and then goes to the photodiode.Changes in the phase of the beat signal determine the changes in the arm length.mechanisms from an arm of the Y, as shown in figure 10.4 (see [10]). Themechanisms provide a very smooth one degree change in the angle between thearms with mainly a one year period.At the centre of each optical bench, shown in figure 10.5 (see [9]), is afreely floating test mass that is protected as much as possible from sources ofspurious accelerations. The basic measurements made by the LISA antenna