(Left) SCExAO team and Nick stand above a deep hole on a hike around HP. (Right) The VAMPIRES team enjoying the view of the lava entry at Volcano national park.
The Vector Vortex team
The vector vortex coronagraph is being developed in collaboration with a team from NASA's Jet Propulsion Laboratories. It is led by Eugene Serabyn and the lead postdoc. is Jonas Kuhn. The following publications offer insightful information about this module:
The COCORO team (8OPM project)
The Coronagraphic Observations with Central-Obscuration Removal Optics (COCORO) project is being pursued as a collaboration between multiple institutes, led by Naoshi Murakami from Hokkaido University, Japan. Key team members include Fumika Oshiyama (Hokkaido Univ.), the SCExAO team, Naoshi Baba (Hokkaido Univ.), Taro Matsuo (Kyoto Univ.), Jun Nishikawa (NAOJ), and Motohide Tamura (Univ. Tokyo). The word "COCORO" means "heart" in Japanese.
This project is motivated by the fact that focal-plane phase-mask coronagraphs theoretically realize perfect rejection of light from a point-like star under ideal conditions (i.e., perfect incoming stellar wavefront without phase aberrations/diffraction affects). However, the coronagraphic performance degrades due to the presence of a secondary mirror and spiders which induce diffraction affects causing residual stellar light to make its way to the detector and potentially mask the presence of a planet (left figure).
(Left) The principle of a focal-plane phase-mask (eight-octant phase mask, 8OPM) coronagraph, and numerical simulations for clear circular and obscured telescope pupils
(Right) Schematic design and pictures of the manufactured CRPs. A result of preliminary laboratory tests is also shown.
To recover some of the coronagraphic performance, we propose using pupil mapping optics called central-obscuration removal plates (CRPs). The CRPs are a pair of convex-concave plates specially designed for converting a centrally-obscured pupil into a clear circular one. The CRPs are made of low-dispersion calcium fluoride (right figure). We also manufactured an eight-octant phase mask (8OPM), one type of focal-plane phase mask, based on photonic-crystal technology. The CRPs and the 8OPM are both optimized for observations in the H band. The manufactured CRPs and 8OPM have been installed into the SCExAO in Sept 2013. The CRP system would be also useful for other types of focal-plane coronagraphic masks, such as a 4-quadrant phase mask (4QPM) and vector vortex mask.
The following publications offer insightful information about this module:
- The 8OPM coronagraph concept: N. Murakami, et. al., 2008, "An eight-octant phase-mask coronagraph," PASP, 120, 1112
- Manufacturing of a photonic-crystal 8OPM: N. Murakami, et. al., 2010, "Achromatic eight-octant phase-mask coronagraph using photonic crystal," ApJ, 714, 772
- SCExAO/8OPM Overview: N. Murakami,et. al., 2010, "An eight-octant phase-mask coronagraph for the Subaru coronagraphic extreme AO (SCExAO) system: system design and expected performance," Proc. SPIE, 7735, 773533.
- Laboratory tests of the CRP system: F. Oshiyama, et. al., 2014, "Central-obscuration removal plates for focal-plane phase-mask coronagraphs with a centrally-obscured telescope," PASP, accepted
The Shaped Pupil team
The shaped pupil coronagraph is being developed in collaboration with a team from Princeton University. It is led by Jeremy Kasdin and includes Tyler Groff, .. . The following publications offer insightful information about this module:
The VAMPIRES team
The Visible Aperture Masking Polarimetric Interferometer for Resolving Exoplanetary Signatures (VAMPIRES) is being developed in collaboration with a team from the University of Sydney, Australia. It is led by Peter Tuthill and supported by PhD students Barnaby Norris, Guillaume Shworer and Paul Stewart. The following publications offer insightful information about this module:
The FIRST team
The Fibered Imager foR a Single Telescope (FIRST) is being developed in collaboration with a team from Observatoire de Paris, led by Guy Perrin. Key team members include Elsa Huby (Universite de Liege), Sylvestre Lacour (Observatoire de Paris), Franck Marchis (SETI Institute), Gaspard Duchene (UC Berkeley), Takayuki Kotani (NAOJ), Olivier Lai (Gemini, NAOJ), Julien Woillez (ESO) and Lucien Gauchet (Observatoire de Paris).
FIRST is a visible light instrument which is based on a novel principle combining the techniques of aperture masking and spatial filtering of the wavefront thanks to single mode fibers (Perrin et al. 2006). The pupil of the telescope is divided into sub-apertures, each feeding one single mode fiber. These fibers only transmit the fundamental (quasi gaussian) mode of the fiber, thus cleaning the wavefront from the spatial phase perturbations (speckles) across the sub-aperture area. The fiber outputs are then organized on a linear non-redundant configuration in order to avoid the blurring of the fringes. The beams are cross-dispersed (spectral resolution of ~300) and recombined on a detector. Data post-processing (Lacour et al. 2007, Huby et al. 2012) then allows the estimation of closure phases (and ultimately complex visibilities) as a function of wavelength, allowing the spectral characterization of the observed target down to the diffraction limit of the telescope. First results have been obtained on binary stars (Huby et al., 2013). The angular resolution achieved at the Subaru telescope will allow the observation of asymmetries at the surface of supergiant stars with the largest apparent diameter (e.g. Betelgeuse).
(Top left) Schematic of the instrument principle for the recombination of 9 sub-apertures
(Top right) Picture of the injection and recombination parts of FIRST instrument as installed at the Subaru Telescope Nasmyth platform.
The two components are only linked via the optical fibers which transport the light from one to another
(Bottom) The instrument as mounted at the Lick Observatory.
|Key Technical Parameters||Value|
|Number of sub-apertures||2 sets of 9 sub-apertures recombined independently|
|Spectral bandwidth||600 - 850 nm|
|Angular resolution||λ/D = 18 mas at 700 nm|
|Field-of-view||~6 λ/D ~ 100 mas|
The following publications offer insightful information about the FIRST instrument and achievements:
- The principle: Perrin, G. et. al., 2006, "High dynamic range imaging by pupil single-mode filtering and remapping", MNRAS, 373, 747P
- The data processing: Lacour, S., et. al., 2007, "High dynamic range imaging with a single-mode pupil remapping system: a self-calibration algorithm for redundant interferometric arrays" MNRAS, 374, 832L
- Laboratory results: Kotani, T., et. al., 2009, "Pupil remapping for high contrast astronomy: results from an optical testbed", Opt. Exp., 17, 1925
- First on-sky results from the 3 m Shane Telescope (Lick Observatory): Huby, E., et. al., 2012, "FIRST, a fibered aperture masking instrument. I. First on-sky test results", A&A, 541A, 55H
- Observations of the Capella binary system: Huby, E., 2013, "FIRST, a fibered aperture masking instrument. II. Spectroscopy of the Capella binary system at the diffraction limit", A&A, 560A, 113H
This is a list of associated press releases:
The MKIDS camera team
The MKIDS camera is being developed in collaboration with a team from the University of California, Santa Barbara. It is led by Ben Mazin and includes Seth Meeker, Matt Strader, Julian van Eyken and others at UCSB, Rebecca Jensen-Clem at Caltech, and Bruce Bumble at JPL.
The MKIDS acronym stands for Microwave Kinetic Inductance Detectors which are an emerging superconducting detector technology capable of noise-free single-photon-counting and low-resolution spectrophotometry across UV, optical, and near-IR wavelengths simultaneously. MKIDs have great potential as integral field units for high-contrast imaging experiments because they are capable of generating noise-free data cubes with arbitrarily short exposures. This allows speckle-reduction post-processing by Chromatic Differential Imaging and by the Dark Speckle technique, a promising speckle removal technique that has previously been limited by the absence of a suitable detector technology. Most importantly, the fast and continuous readout of MKIDs allows for focal plane speckle control at rates high enough to track speckles with ~1s lifetimes, removing the current dominant noise-source in direct imaging experiments.
The first UVOIR MKID camera, the ARray Camera for Optical to Near-infrared Spectrophotometry (ARCONS), saw first light at Palomar Observatory in 2011 and has since demonstrated the first science results from any MKID camera. The MKID camera for SCExAO will feature an upgraded detector array, with 5x as many pixels as ARCONS, optimized for a target bandwidth of 0.7-1.4 microns, and an overhauled readout system integrated directly with the wavefront control for extremely fast focal-plane feedback.
(Left) The UCSB team with ARCONS at the Palomar 200" telescope. (Right) A prototype of the 10,000 pixel MKID array that will serve as this camera's focal plane.
The following publications offer insightful information about this module:
- First paper on MKIDs: Day et al. 2003, "A broadband superconducting detector suitable for use in large arrays" Nature, 425, 817.
- Optical MKIDs: Mazin et al. 2012, "A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics" Optics Express, 20, 2, 1503.
- MKIDs readout: McHugh et al. 2012, "A readout for large arrays of microwave kinetic inductance detectors" Rev. Sci. Inst., 83, 044702
- ARCONS: Mazin et al. 2013, "ARCONS: A 2024 pixel optical through near-IR cryogenic imaging spectrophotometer" PASP, 125, 933
- First science with MKIDs: Strader et al. 2013, "Excess optical enhancement observed with ARCONS for early crab giant pulses" ApJL, 779, 1
The CHARIS team
CHARIS is an integral field spectrograph being purpose built to work with SCExAO. A team from Princeton University are leading the effort headed by Jeremy Kasdin. The team includes Tyler Groff, Mary Anne Peters, Michael Galvin, Michael McElwain and others. The following publications offer insightful information about this module:
The SEEDs team
Science observations are being coordinated with members of the SEEDS community. We work closely with Motohide Tamura, Thayne Currie, Christian Thalmann, Michael McElwain, Markus Janson, John Wisniewshi, Thomas Henning, Ed Turner, Masayuki Kuzuhara, Jill Knapp as well as the rest of the SEEDS members. A document outlining the strategy of the SEEDS survey can be found here. More information can be found here. The following publications offer insightful information into their work: