Proof masses and optical benches

Schematic diagram of proof-masses-plus-optical-benches for a LISA spacecraft. The left-hand bench reads out the Doppler signals y₃₁ (from spacecraft 2, bounced off the left proof mass, read out using laser and photodetector on the left optical bench) and z₃₁ (from the right optical bench, bounced off the right-hand proof mass, redirected to the left-hand bench and read out with the laser/photodetector on the left bench). The right hand bench analogously reads out y₂₁ and z₂₁. The random velocities of the two proof masses and two optical benches are indicated (lower case v_i for the proof masses and upper case V_i for the optical benches).

Figure from Tinto, Estabrook & Armstrong (2002)