At the University of Galway Nicholas Devaney and Fiona Kenny (now at Atlantic Technological University) have studied Beam propagation simulations for LISA in the presence of telescope aberrations.
Above is an example from a simulation showing pathlength errors introduced by random combinations of defocus and astigmatism in the transmit telescope where there is +/- 0.1 microradians of tilt jitter, for different beam types (uniform or Gaussian).