2012 - 2013: AAO Extended Studentship to contine work on SAMI as a Pre-Doc 2008 - 2012: BSc (Hons) Astrophysics with Research Year (First Class Honours at the University of Hertfordshire, UK) 2010 - 2011: Research Year at the University of Sydney and Australian Astronomical Observatory working on the new multiplex integral field spectral for the AAT "SAMI" -------------------- Authored Papers: 1. Richards, et al., 2012, BASIS: Bayfordbury Single-object Integral Field Spectrograph, SPIE Astronomical Telescopes & Instrumentation Conference Proceedings 8446.82 (http://to.ly/dQ4c) 2. Fogarty, et al., 2012, Data analysis and first science with the Sydney-AAO multi-object IFS (SAMI), SPIE Astronomical Telescopes & Instrumentation Conference Proceedings 8446.211 3. Bryant, et al., 2012, SAMI: a new multi-object IFS for the Anglo-Australian Telescope, SPIE Astronomical Telescopes & Instrumentation Conference Proceedings 8446.31 4. Croom, et al., 2012, The Sydney-AAO Multi-object Integral field spectrograph (SAMI), Monthly Notices of the Royal Astronomical Society 421 (1) p872 (Paper: http://to.ly/eln8, Article: http://to.ly/b6wz) 5. Fischer, et al., 2011, A Photonic Integrated Dual-Arm Spectrograph, White Paper for KECK 2011 Instrument Upgrade Review, 2nd Round only
Assisted Papers: 1. Saward, et al., 2012, Keeping Staff and Students Together - Challenges in Extending the Virtual Learning Environment into Social Networks, International Blended Learning conference 2012 2. Thompson, et al., 2010, A search for debris disks in the Herschel-ATLAS, Astronomy & Astrophysics 518 id.L134 (http://to.ly/eln8)
Conference Posters: 1. Richards, et al., 2012, Integral field spectroscopy on small aperture telescopes, UK & Germany National Astronomy Meeting 2012 (http://to.ly/cAY7) 2. Richards, et al., 2012, BASIS: Bayfordbury Single-object Integral Field Spectrograph, SPIE Astronomical Telescopes & Instrumentation Conference Proceedings 8446.82
Publications (11)
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Using single-mode fibres in astronomy enables revolutionary techniques including single-mode interferometry and spectroscopy. However, injection of seeing-limited starlight into single mode photonics is extremely difficult. One solution is Adaptive Injection (AI). The telescope pupil is segmented into a number of smaller subapertures each with size ~ r0, such that seeing can be approximated as a single tip / tilt / piston term for each subaperture, and then injected into a separate fibre via a facet of a segmented MEMS deformable mirror. The injection problem is then reduced to a set of individual tip tilt loops, resulting in high overall coupling efficiency.
The Australian Astronomical Observatory is currently investigating the use of adaptive optics technologies for the 3.9m Anglo-Australian Telescope at Siding Spring Observatory. It might be that ground-layer or multi-object adaptive optics is beneficial for the Anglo-Australian Telescope (seeing ∼1.5"). Key to achieving this goal is an adaptive optics test-bench developed for laboratory experiments and on-sky demonstration. The test-bench provides a facility to demonstrate on-sky natural guide star adaptive optics as well as second stage correction with active injection into single mode waveguides. The test-bench provides wide field access of up to 20 arcminutes for testing our plug-plate distributed wavefront sensors. Data has been collected in a range of seeing conditions where closed-loop corrections were performed. We present the design, results and plans for the adaptive optics on-sky demonstrator.
The image quality of a fluid atmospheric dispersion corrector (FADC) is analysed and presented.
The FADC is located at Cassegrain focus to correct the atmospheric dispersion passively at
Australian astronomical telescope. It is shown that an FADC with diameter 10mm can correct
the atmospheric dispersion over a field diameter of 20” in the spectral range between 0.4μm to
1μm, and to zenith distance of 52º. The FADC image quality is well controlled within 0.27” for
the telescope operation range. The residual atmospheric dispersion is 0.1” for on axis field and
0.20” at the extreme field (10”) at zenith distance of 52º. The FADC-induced shift in the
centroids of the images is less than 10μm (0.067”). The FADC can work up to the field of 5’ at
Cassegrain focus and its image quality is similar to its on axis performance. Our on-sky
demonstration results agree well with our simulations.
A miniature curvature wavefront sensor with a coherent fiber image bundle is proposed in which a miniature lateral displacement beamsplitter is designed to obtain the intra- and extra- focus images from a telescope simultaneously at its exit. The two images are received and relayed by two coherent fiber image bundles. The relayed images are then re-imaged to one camera and processed to obtain the input wavefront at telescope pupil. The whole device is quite compact and can be driven by a “Starbug” fiber positioning device currently under development within the Australian Astronomical Observatory. In this paper, the performance of the proposed sensor is investigated in details by applying a simulated atmospheric turbulence at the telescope pupil plane. We study the offset distance of two image measurement planes, fiber core size, fiber fill factor and the magnitude of natural guide star effects to its performance. This study provides guidance to the sensor design.
MANIFEST is a fibre feed system for the Giant Magellan Telescope that, coupled to the seeing-limited instruments
GMACS and G-CLEF, offers qualitative and quantitative gains over each instrument’s native capabilities in terms of
multiplex, field of view, and resolution. The MANIFEST instrument concept is based on a system of semi-autonomous
probes called “Starbugs” that hold and position hundreds of optical fibre IFUs under a glass field plate placed at the
GMT Cassegrain focal plane. The Starbug probes feature co-axial piezoceramic tubes that, via the application of
appropriate AC waveforms, contract or bend, providing a discrete stepping motion. Simultaneous positioning of all
Starbugs is achieved via a closed-loop metrology system.
Hector is an instrument concept for a multi integral-field-unit spectrograph aimed at obtaining a tenfold increase in
capability over the current generation of such instruments. The key science questions for this instrument include how do
galaxies get their gas, how is star formation and nuclear activity affected by environment, what is the role of feedback,
and what processes can be linked to galaxy groups and clusters. The baseline design for Hector incorporates multiple
hexabundle fibre integral-field-units that are each positioned using Starbug robots across a three-degree field at the
Anglo-Australian Telescope. The Hector fibres feed dedicated fixed-format spectrographs, for which the parameter space
is currently being explored.
The ability to position multiple miniaturized wavefront sensors precisely over large focal surfaces are advantageous to
multi-object adaptive optics. The Australian Astronomical Observatory (AAO) has prototyped a compact and lightweight
Shack-Hartmann wavefront-sensor that fits into a standard Starbug parallel fibre positioning robot. Each device makes
use of a polymer coherent fibre imaging bundle to relay an image produced by a microlens array placed at the telescope
focal plane to a re-imaging camera mounted elsewhere. The advantages of the polymer fibre bundle are its high-fill
factor, high-throughput, low weight, and relatively low cost. Multiple devices can also be multiplexed to a single lownoise
camera for cost efficiencies per wavefront sensor. The use of fibre bundles also opens the possibility of
applications such as telescope field acquisition, guiding, and seeing monitors to be positioned by Starbugs. We present
the design aspects, simulations and laboratory test results.
TAIPAN is a spectroscopic instrument designed for the UK Schmidt Telescope at the Australian Astronomical Observatory. In addition to undertaking the TAIPAN survey, it will serve as a prototype for the MANIFEST fibre positioner system for the future Giant Magellan Telescope. The design for TAIPAN incorporates up to 300 optical fibres situated within independently-controlled robotic positioners known as Starbugs, allowing precise parallel positioning of every fibre, thus significantly reducing instrument configuration time and increasing observing time. We describe the design of the TAIPAN instrument system, as well as the science that will be accomplished by the TAIPAN survey. We also highlight results from the on-sky tests performed in May 2014 with Starbugs on the UK Schmidt Telescope and briefly introduce the role that Starbugs will play in MANIFEST.
PIMMS échelle is an extension of previous PIMMS (photonic integrated multimode spectrograph) designs, enhanced by using an échelle diffraction grating as the primary dispersing element for increased spectral band- width. The spectrograph operates at visible wavelengths (550 to 780nm), and is capable of capturing ~100 nm of R > 60, 000 (λ/(triangle)λ) spectra in a single exposure. PIMMS échelle uses a photonic lantern to convert an arbitrary (e.g. incoherent) input beam into N diffraction-limited outputs (i.e. N single-mode fibres). This allows a truly diffraction limited spectral resolution, while also decoupling the spectrograph design from the input source.
Here both the photonic lantern and the spectrograph slit are formed using a single length of multi-core fibre. A 1x19 (1 multi-mode fiber to 19 single-mode fibres) photonic lantern is formed by tapering one end of the multi-core fibre, while the other end is used to form a TIGER mode slit (i.e. for a hexagonal grid with sufficient spacing and the correct orientations, the cores of the multi-core fibre can be dispersed such that they do not overlap without additional reformatting). The result is an exceptionally compact, shoebox sized, spectrograph that is constructed primarily from commercial off the shelf components. Here we present a brief overview of the échelle spectrograph design, followed by results from on-sky testing of the breadboard mounted version of the spectrograph at the ‘UK Schmidt Telescope’.
We present an inexpensive (<US$500) and easily replicable integral field unit for use on small aperture telescopes.
Based on a commercial small spectrograph (SBIG Self-Guiding Spectrograph) and a 37 optical fibre bundle integral field
unit with each fibre having 50μm cores and a pitch of 125μm. It has an overall field-of-view of 40 arc seconds
(2.6arcsec/core), a resolution of 9Å from 3995Å to 7170Å and an average system efficiency of 9%, yielding a signal-tonoise
ratio of 10 for a 20min exposure of a 13mag/arcsec2 source. Still in commissioning, we present first light
observations of Vega and M57.
SAMI (Sydney-AAO Multi-object Integral field spectrograph) has the potential to revolutionise our understanding
of galaxies, with spatially-resolved spectroscopy of large numbers of targets. It is the first on-sky application of
innovative photonic imaging bundles called hexabundles, which will remove the aperture effects that have biased
previous single-fibre multi-object astronomical surveys. The hexabundles have lightly-fused circular multi-mode
cores with a covering fraction of 73%. The thirteen hexabundles in SAMI, each have 61 fibre cores, and feed
into the AAOmega spectrograph at the Anglo-Australian Telescope (AAT). SAMI was installed at the AAT in
July 2011 and the first commissioning results prove the effectiveness of hexabundles on sky. A galaxy survey of
several thousand galaxies to z 0.1 will begin with SAMI in mid-2012.
