  Searching for nearby habitable worlds with direct imaging and spectroscopy
will require a telescope large enough to provide angular resolution and
sensitivity to planets around a significant sample of stars. Segmented
telescopes are a compelling option to obtain such large apertures. However,
these telescope designs have a complex geometry (central obstruction, support
structures, segmentation) that makes high-contrast imaging more challenging. We
are developing a new high-contrast imaging testbed at STScI to provide an
integrated solution for wavefront control and starlight suppression on complex
aperture geometries. We present our approach for the testbed optical design,
which defines the surface requirements for each mirror to minimize the
amplitude-induced errors from the propagation of out-of-pupil surfaces. Our
approach guarantees that the testbed will not be limited by these Fresnel
propagation effects, but only by the aperture geometry. This approach involves
iterations between classical ray-tracing optical design optimization, and
end-to-end Fresnel propagation with wavefront control (e.g. Electric Field
Conjugation / Stroke Minimization). The construction of the testbed is planned
to start in late Fall 2013.
