LISA : Pointing sensor development stand

We are developing a pointing sensor as part of the technology development effort for the Laser Interferometer Space Antenna (LISA) mission. The sensor will measure the angle between two beams, by measuring the phase difference in the heterodyne frequency on different sides of the pupil plane. In LISA, one beam would be from the local laser, while the other beam comes from a different spacecraft. The beam coming from the other space craft will have a Doppler shift due to changes in the orbits of the satellites. The phase difference across the aperture will be measured to align the incoming and outgoing beams.