Emiel H. Por

NHFP Sagan fellow at STScI

Emiel Por started his education at Leiden University with a double Bachelor’s degree in Physics and Astronomy in 2013 and a Master’s degree in Astronomical Instrumentation in 2016. He continued at Leiden University and received his PhD in Astronomy in December 2020. In 2021 he started as a Sagan fellow at the Space Telescope Science Institute.

Emiel’s research focuses on advanced instrumentation for the direct imaging of exoplanets for both ground- and space-based telescopes. He develops novel coronagraph solutions and methods for post-coronagraphic wavefront sensing. Segmented primary mirrors, such as the one proposed for LUVOIR, require that all segments stay aligned to within a few picometers during a coronagraphic observation. Therefore, besides a high-performance coronagraph, high-order wavefront sensing and control will be necessary for future giant segmented space telescopes. As an NHFP Sagan fellow at the Space Telescope Science Institute, Emiel works on developing novel coronagraph solutions that jointly optimize both contrast and wavefront sensing and control.

news [archive]

Feb 22, 2021	Released HCIPy 0.4.0.
Jan 15, 2021	Started as a Sagan Fellow at Space Telescope Science Institute in Baltimore, MD.
Dec 11, 2020	Successfully defended my PhD dissertation at Leiden University!
Apr 2, 2020	Released HCIPy 0.3.1.
Mar 25, 2020	Was awarded an NHFP Sagan fellowship at the Space Telescope Science Institute!

selected publications [full list]

ApJ

Phase-apodized-pupil Lyot Coronagraphs for Arbitrary Telescope Pupils

Por, Emiel H.

ApJ 888, 127 (2020)

abstract ADS PDF

The phase-apodized-pupil Lyot coronagraph (PAPLC) is a pairing of the apodized-pupil Lyot coronagraph and the apodizing phase plate (APP) coronagraph. We describe a numerical optimization method to obtain globally optimal solutions for the phase apodizers for arbitrary telescope pupils, based on the linear map between complex-amplitude transmission of the apodizer and the electric field in the post-coronagraphic focal plane. PAPLCs with annular focal-plane masks and point-symmetric dark zones perform analogous to their corresponding APLCs. However, with a knife-edge focal-plane mask and one-sided dark zones, the PAPLC yields inner working angles as close as 1.4λ/D at contrasts of 10−10 and a maximum post-coronagraphic throughput of >75% for telescope apertures with central obscurations of up to 30%. We present knife-edge PAPLC designs optimized for the VLT/SPHERE instrument and the LUVOIR-A aperture. These designs show that the knife-edge PAPLC retains its performance, even for realistic telescope pupils with struts, segments, and non-circular outer edges.
SPIE

High Contrast Imaging for Python (HCIPy): an open-source adaptive optics and coronagraph simulator

Por, Emiel H., Haffert, Sebastiaan Y., Radhakrishnan, Vikram M., Doelman, David S., van Kooten, Maaike, and Bos, Steven P.

Proc. SPIE 10703 (2018)

abstract ADS PDF Code Poster

HCIPy is a package written in Python for simulating the interplay between wavefront control and coronagraphic systems. By defining an element which merges values/coefficients with its sampling grid/modal basis into a single object called Field, this minimizes errors in writing the code and makes it clearer to read. HCIPy provides a monochromatic Wavefront and defines a Propagator that acts as the transformation between two wavefronts. In this way a Propagator acts as any physical part of the optical system, be it a piece of free space, a thin complex apodizer or a microlens array. HCIPy contains Fraunhofer and Fresnel propagators through free space. It includes an implementation of a thin complex apodizer, which can modify the phase and/or amplitude of a wavefront, and forms the basis for more complicated optical elements. Included in HCIPy are wavefront errors (modal, power spectra), complex apertures (VLT, Keck or Subaru pupil), coronagraphs (Lyot, vortex or apodizing phase plate coronagraph), deformable mirrors, wavefront sensors (Shack-Hartmann, Pyramid, Zernike or phase-diversity wavefront sensor) and multi-layer atmospheric models including scintillation). HCIPy aims to provide an easy-to-use, modular framework for wavefront control and coronagraphy on current and future telescopes, enabling rapid prototyping of the full high-contrast imaging system. Adaptive optics and coronagraphic systems can be easily extended to include more realistic physics. The package includes a complete documentation of all classes and functions, and is available as open-source software.