The LTP optical bench is at the core of the optical metrology system
The ultra-stable optical bench (designed and built by University Glasgow) is at the core of the optical metrology system on the LTP. Two laser beams with slightly differing frequencies are injected onto the bench through custom made fibre injectors. The beams are split multiple times and follow various paths before being recombined at four interference points. The four main outputs come from:
The optical inteference of each of the four interferometers is read-out by quadrant photodiodes whose signals are then measured by the phasemeter and further processed in the payload computer (the DMU) to produce longitudinal and attitude measurements of two free-falling test masses.