Context.
The detection and characterization of Earth-like exoplanets (exoEarths) from space requires exquisite wavefront stability at contrast levels of 10
−10
. On segmented telescopes in ...particular, aberrations induced by co-phasing errors lead to a light leakage through the coronagraph, deteriorating the imaging performance. These need to be limited in order to facilitate the direct imaging of exoEarths.
Aims.
We perform a laboratory validation of an analytical tolerancing model that allows us to determine wavefront error requirements in the 10
−6
− 10
−8
contrast regime for a segmented pupil with a classical Lyot coronagraph. We intend to compare the results to simulations, and we aim to establish an error budget for the segmented mirror on the High-contrast imager for Complex Aperture Telescopes (HiCAT) testbed.
Methods.
We use the Pair-based Analytical model for Segmented Telescope Imaging from Space to measure a contrast influence matrix of a real high-contrast instrument, and use an analytical model inversion to calculate per-segment wavefront error tolerances. We validate these tolerances on the HiCAT testbed by measuring the contrast response of segmented mirror states that follow these requirements.
Results.
The experimental optical influence matrix is successfully measured on the HiCAT testbed, and we derive individual segment tolerances from it that correctly yield the targeted contrast levels. Further, the analytical expressions that predict a contrast mean and variance from a given segment covariance matrix are confirmed experimentally.
We use Sloan Digital Sky Survey (SDSS) photometry of 73 million stars to simultaneously constrain best-fit main-sequence stellar spectral energy distribution (SED) and amount of dust extinction along ...the line of sight toward each star. Using a subsample of 23 million stars with Two Micron All Sky Survey (2MASS) photometry, whose addition enables more robust results, we show that SDSS photometry alone is sufficient to break degeneracies between intrinsic stellar color and dust amount when the shape of extinction curve is fixed. Our results are in good agreement with the extinction normalization given by the Schlegel et al. (SFD) dust maps at high northern Galactic latitudes, but indicate that the SFD extinction map appears to be consistently overestimated by about 20% in the southern sky, in agreement with recent study by Schlafly et al. We make these best-fit parameters, as well as all the input SDSS and 2MASS data, publicly available in a user-friendly format.
Laboratory testbeds are an integral part of conducting research and developing technology for high-contrast imaging and extreme adaptive optics. There are a number of laboratory groups around the ...world that use and develop resources that are imminently required for their operations, such as software and hardware controls. The CAOTIC (Community of Adaptive OpTics and hIgh Contrast testbeds) project is aimed to be a platform for this community to connect, share information, and exchange resources in order to conduct more efficient research in astronomical instrumentation, while also encouraging best practices and strengthening cross-team connections. In these proceedings, we present the goals of the CAOTIC project, our new website, and we focus in particular on a new approach to teaching version control to scientists, which is a cornerstone of successful collaborations in astronomical instrumentation.
Context: The detection and characterization of Earth-like exoplanets (exoEarths) from space requires exquisite wavefront stability at contrast levels of \(10^{-10}\). On segmented telescopes in ...particular, aberrations induced by cophasing errors lead to a light leakage through the coronagraph, deteriorating the imaging performance. These need to be limited in order to facilitate the direct imaging of exoEarths. Aims: We perform a laboratory validation of an analytical tolerancing model that allows us to determine wavefront error requirements in the \(10^{-6} - 10^{-8}\) contrast regime, for a segmented pupil with a classical Lyot coronagraph. We intend to compare the results to simulations, and we aim to establish an error budget for the segmented mirror on the High-contrast imager for Complex Aperture Telescopes (HiCAT) testbed. Methods: We use the Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS) to measure a contrast influence matrix of a real high contrast instrument, and use an analytical model inversion to calculate per-segment wavefront error tolerances. We validate these tolerances on the HiCAT testbed by measuring the contrast response of segmented mirror states that follow these requirements. Results: The experimentally measured optical influence matrix is successfully measured on the HiCAT testbed, and we derive individual segment tolerances from it that correctly yield the targeted contrast levels. Further, the analytical expressions that predict a contrast mean and variance from a given segment covariance matrix are confirmed experimentally.
The differential Optical Transfer Function (dOTF) is a focal plane wavefront sensing method that uses a diversity in the pupil plane to generate two different focal plane images. The difference of ...their Fourier transforms recovers the complex amplitude of the pupil down to the spatial scale of the diversity. We produce two simultaneous PSF images with diversity using a polarizing filter at the edge of the telescope pupil, and a polarization camera to simultaneously record the two images. Here we present the first on-sky demonstration of polarization dOTF at the 1.0m South African Astronomical Observatory telescope in Sutherland, and our attempt to validate it with simultaneous Shack-Hartmann wavefront sensor images.
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