First On‐Sky High‐Contrast Imaging with an Apodizing Phase Plate

Abstract

We present the first astronomical observations obtained with an apodizing phase plate (APP). The plate is designed to suppress the stellar diffraction pattern by 5 mag from 2 À 9k/D over a 180 region. Stellar images were obtained in the M 0 band (k c ¼ 4:85 m) at the MMTO 6.5 m telescope, with adaptive wave-front correction made with a deformable secondary mirror designed for low thermal background observations. The measured point-spread function (PSF) shows a halo intensity of 0.1% of the stellar peak at 2k/D (0.36 00 ), tapering off as r À5=3 out to radius 9k/D. Such a profile is consistent with residual errors predicted for servo lag in the AO system. We project a 5 contrast limit, set by residual atmospheric fluctuations, of 10.2 mag at 0.36 00 separation for a 1 hr exposure. This can be realized if static and quasi-static aberrations are removed by differential imaging, and is close to the sensitivity level set by thermal background photon noise for target stars with M 0 > 3. The advantage of using the phase plate is the removal of speckle noise caused by the residuals in the diffraction pattern that remain after PSF subtraction. The APP gives higher sensitivity over the range (2Y5) k/D than direct imaging techniques.

End-to-end simulations of the E-ELT/METIS coronagraphs

“…1,3,23 It is a pupil-plane one-stage optical device, consisting of an anti-symmetric phase pattern (see Fig. 4(h)) that redistributes the light in the image plane, creating a dark hole.…”

Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph

“…Improved sensitivity in a given discovery region may be achieved by designing a dark hole in the point spread function (PSF) of an on-axis source (see . This approach has found success in the apodizing phase plate (APP) coronagraph (Codona & Angel 2004;Kenworthy et al 2007Kenworthy et al , 2010. In comparison to a focal plane coronagraph, the APP uses a pupil-plane phase mask to produce a dark hole in the spatially invariant PSF rather than reducing the amount of onaxis starlight reaching the image plane.…”

An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme Adaptive Optics System

“…The bulk of the stellar point-spread function (PSF) can then be attenuated by a few orders of magnitudes using various types of coronagraphs, located in intermediate pupil- (Kenworthy et al 2007) or focalplane(s) (Rouan et al 2000;Mawet et al 2010) upstream of the scientific focal plane array. In addition, to improve residual PSF subtraction and further reject fainter NCPA speckles, advanced observing strategies have to be employed, such as e.g., angular differential imaging (ADI) (Marois et al 2006), spectral-/dual-band differential imaging (SDI/DBI) (Lafrenière et al 2007a), coherent differential imaging (CDI) (Bottom et al 2017), polarimetric differential imaging (PDI) (Schmid et al 2017), machine learning (Gomez Gonzales et al 2016), and often a combination of those.…”