  We theoretically investigate the influence of gravity on laser light in a
hemispherical optical cavity, operating on Earth. The propagation of light in
such a cavity is modeled by a Gaussian beam, affected by the Earth's
gravitational field. On laboratory scale, this field is described by the
spacetime of homogeneous gravity, known as Rindler spacetime. In that
spacetime, the beam is bent downwards and acquires a height dependent phase
shift. As a consequence the phase fronts of the laser light differ from those
of a usual Gaussian beam. Assuming that the initial beam enters the cavity
along its symmetry axis, these gravitational effects cause variations of the
beam phase with every cavity round trip. Detailed calculations are performed to
investigate how these phase variations depend on the beam parameters and the
cavity setup. Moreover, we discuss the implications of our findings for cavity
calibration techniques and cavity-based laser stabilization procedures.
