  We propose the segmented Large Millimeter Telescope (LMT/GTM),as the largest
spatial light modulator capable of producing vortex beams of integer
topological charge. This observing mode could be applied for direct exoplanet
searches in the millimeter or submillimeter regimes. We studied the stability
of the vortex structure against aberrations and diffraction effects inherent to
the size and segmented nature of the collector mirror. In the presence of low
order aberrations the focal distribution of the system remains stable. Our
results show that these effects depend on the topological charge of the vortex
and the relative orientation of the aberration with respect to the antenna
axis. Coma and defocus show no large effects in the image at the focal plane,
nevertheless the system is very sensitive to astigmatism. Heat turbulence,
simulated by random aberrations, shows that the system behaves in a similar way
as astigmatism dissociating the vortices. We propose the Segmented Vortex
Telescope as a novel approach for the detection of giant planets outside
circumstellar disks around nearby stars. Since our results are applicable to
other facilities with segmented surfaces, we suggest that this idea should be
considered as a regular observation mode complementary to interferometric
methods.
