Influence of Seidel distortion on combining beams from a phased telescope array.

When beams from an array of a focal telescopes are presented to a beam-combining telescope, tilt errors of the beam wave fronts with respect to the combined wave front place limits on the achievable field of view (FOV); these limits, to the best of our knowledge, have not previously been correctly described in the literature. We show that if the front-end telescopes have just the right Seidel distortion coefficient, then tilt error does not limit the FOV. If this is not the case, at least small FOV's can still be obtained, even if the FOV is not centered on the on-axis direction.