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15 September 2011 Stability error budget for an aggressive coronagraph on a 3.8 m telescope
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We evaluate in detail the stability requirements for a band-limited coronagraph with an inner working angle as small as 2 λ/D coupled to an off-axis, 3.8-m diameter telescope. We have updated our methodologies since presenting a stability error budget for the Terrestrial Planet Finder Coronagraph mission that worked at 4 λ/D and employed an 8th-order mask to reduce aberration sensitivities. In the previous work, we determined the tolerances relative to the total light leaking through the coronagraph. Now, we separate the light into a radial component, which is readily separable from a planet signal, and an azimuthal component, which is easily confused with a planet signal. In the current study, throughput considerations require a 4th-order coronagraph. This, combined with the more aggressive working angle, places extraordinarily tight requirements on wavefront stability and opto-mechanical stability. We find that the requirements are driven mainly by coma that leaks around the coronagraph mask and mimics the localized signal of a planet, and pointing errors that scatter light into the background, decreasing SNR. We also show how the requirements would be relaxed if a low-order aberration detection system could be employed.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stuart B. Shaklan, Luis Marchen, John Krist, and Mayer Rud "Stability error budget for an aggressive coronagraph on a 3.8 m telescope", Proc. SPIE 8151, Techniques and Instrumentation for Detection of Exoplanets V, 815109 (15 September 2011);

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