Far field simulation for LISA

The Laser Interferometer Space Antenna (LISA) pushes the limit of interferometric precision for gravitational wave detection. Three spacecrafts exchange laser beams between them to measure subatomic length changes between free falling test masses separated by 2.5 gigameters. Our group uses high order Hermite-Gauss (HG) mode expansion, with analytically obtained mode coefficients, to provide quick and accurate renderings of the exchanged fields. We have used this to calculate tilt-to-length couplings from spacecraft pointing jitter, and can easily adjust the results to account for any potential mirror or phase distortions represented as Zernike polynomials. With this we intend to develop a means for fast and reliable representation of beams at any point along the optical chain of LISA.