Preliminary Study Of A 10-m Baseline Heterodyne Laser Interferometer For Space Laser Ranging

Space laser ranging refers to technology that utilizes laser interferometer to measure the relative displacement and/or absolute distance between two objects (or spacecrafts) moving in space. This technology can be used for orbit determination of satellites, deep space exploration, inter-satellite optical communication, and frontiers of fundamental physics. The development of the heterodyne laser interferometer with nanometer precision for inter-satellite range/range-rate monitoring will open up a new window for researchers involved in physics and geophysics. ESA and NASA are carrying out LISA and GRACE follow-on missions for gravitational waves detection and Earth's gravity recovery, respectively. In order to verify the validity of key technologies required, a testing satellite, known as LISA Pathfinder, will be launched in 2012.Developing ultra-precision heterodyne laser interferometer for inter-satellite laser ranging provides a strong driving force for strengthening the precision measurement technology in China and for further underpinning the development of space technology and fundamental research. In this work, a transponder-type inter-satellite laser ranging system with homodyne optical phase-locked loop is proposed. In order to demonstrate the validity of the measurement scheme, a 10-m prototype of heterodyne laser interferometer had been built up at the cave laboratory of Center for Gravitational Experiments in HUST. The preliminary results show that a resolution of better than 5 nm had been achieved.