  A coronagraphic starlight suppression system situated on a future flagship
space observatory offers a promising avenue to image Earth-like exoplanets and
search for biomarkers in their atmospheric spectra. One NASA mission concept
that could serve as the platform to realize this scientific breakthrough is the
Large UV/Optical/IR Surveyor (LUVOIR). Such a mission would also address a
broad range of topics in astrophysics with a multiwavelength suite of
instruments. The apodized pupil Lyot coronagraph (APLC) is one of several
coronagraph design families that the community is assessing as part of NASAs
Exoplanet Exploration Program Segmented aperture coronagraph design and
analysis (SCDA) team. The APLC is a Lyot-style coronagraph that suppresses
starlight through a series of amplitude operations on the on-axis field. Given
a suite of seven plausible segmented telescope apertures, we have developed an
object-oriented software toolkit to automate the exploration of thousands of
APLC design parameter combinations. This has enabled us to empirically
establish relationships between planet throughput and telescope aperture
geometry, inner working angle, bandwidth, and contrast level. In parallel with
the parameter space exploration, we have investigated several strategies to
improve the robustness of APLC designs to fabrication and alignment errors. We
also investigate the combination of APLC with wavefront control or complex
focal plane masks to improve inner working angle and throughput. Preliminary
scientific yield evaluations based on design reference mission simulations
indicate the APLC is a very competitive concept for surveying the local
exoEarth population with a mission like LUVOIR.
