When one creates a hemispherical laser cavity, using one flat and one concave mirror, does the beam image invert each time it makes a round trip? I know when passing through the focus of a lens/mirror, such as in a 4f image relay telescope, an image inversion occurs. If you were to look at the "unfolded" diagram of the hemispherical cavity it would look like an image inversion occurs each round trip, but I think that violates the conditions of a resonator that the beam must repeat itself. I can see how in a confocal/concentric cavity the beam will transverse the focus twice canceling out this inversion (Siegman p.842), but I don't see how this would work for a hemispherical cavity.
