Coupling of wavefront errors and pointing jitter in the LISA interferometer: misalignment of the interfering wavefronts

The laser interferometer space antenna is a foreseen space-based gravitational wave detector, which aims to detect 10^−20 strains in the frequency range from 0.1 mHz to 1 Hz. It is a triangular constellation of three spacecraft, with equal sides of 2.5 × 10^9 m, where every spacecraft hosts a pair of telescopes that simultaneously transmit and receive laser beams measuring the constellation arms by heterodyning the received wavefronts with local references. Due to the spacecraft and constellation jitters, the interfering (received and local) wavefronts become misaligned. We investigate analytically the coupling between misalignments and aberrations of the interfering wavefronts and estimate the relevant contribution to the noise of the heterodyne signal.