The ESO Extremely Large Telescope (ELT) has been in construction since 2014. In parallel with the construction of the telescope, ESO has entered into agreements with consortia in the ESO member states to build the first instruments for that telescope. To meet the telescope science goals, the ambitious instrument plan includes two instruments for first light: an optical to near-infrared integral field spectrograph with a dedicated adaptive optics system (HARMONI) and a near-infrared camera with simple spectrograph (MICADO) behind a multi-conjugate adaptive optics module (MAORY). The next instrument will be a mid-infrared imager and spectrograph (METIS). Plans to follow this first suite of instruments include a high-resolution spectrograph (HIRES) and a multi-object spectrograph (MOSAIC). Technology development is underway to prepare for building the ELT Planetary Camera and Spectrograph. An overview of the telescope and its instruments is given.
Today several methods are developed and used to integrate structural FEA and optical analyses results, enabling detailed prediction of our instrument performance. This publication gives an overview of some of these developments and the choices and challenges that currently exist without claiming to be complete. The focus is on the combination of Structural, Thermal and Optical Performance analyses, also known as ‘STOP’. These analysis solutions are available for projects large or small and can be combined with existing analysis packages.
Challenges identified related to start using STOP analysis are related to knowing which S/W solutions are available, and secondly how to define the integrated analysis process that fits with existing ‘design and analyses’ experience.
These challenges and implementation options are listed in this publication with the aim to encourage the integration of engineering analysis. By applying this integrated analysis process, the risk of finding mistakes and design flaws late in the project are reduced, avoiding delays and additional costs.
ERIS is an instrument that will both extend and enhance the fundamental diffraction limited imaging and spectroscopy capability for the VLT. It will replace two instruments that are now being maintained beyond their operational lifetimes, combine their functionality on a single focus, provide a new wavefront sensing module that makes use of the facility Adaptive Optics System, and considerably improve their performance. The instrument will be competitive with respect to JWST in several regimes, and has outstanding potential for studies of the Galactic Center, exoplanets, and high redshift galaxies. ERIS had its final design review in 2017, and is expected to be on sky in 2020. This contribution describes the instrument concept, outlines its expected performance, and highlights where it will most excel.
In this paper we will report on the status of the instrumentation project for the European Southern Observatory's Extremely Large Telescope (ELT). Three instruments are in the construction phase: HARMONI, MICADO and METIS. The multi-conjugate adaptive optics system for MICADO, MAORY, is also under development. Preliminary Design Reviews of all of these systems are planned to be completed by mid-2019. The construction of a laser tomographic module for HARMONI is part of "Phase 2" of the ELT: the design has been advanced to Preliminary Design level in order to define the interface to the HARMONI spectrograph. Preparations for the next instruments have also been proceeding in parallel with the development of these instruments. Conceptual design studies for the multi-object spectrograph MOSAIC, and for the high resolution spectrograph HIRES have been completed and reviewed. We present the current design of each of these instruments and will summarise the work ongoing at ESO related to their development.
Described is the M1 segment support, as designed by TNO in the period 2015-2016. The design has significantly changed and improved compared to the earlier designs. During the period 2009-2010 prototypes for the primary mirror support of the E-ELT have been developed. These have been extensively tested by ESO. Design improvement were found to be necessary, especially in the field of manufacturability and maintainability. Furthermore, the technical performance had to improve in specific areas as well. This has evolved into a new specifications which have resulted in a new design for the segment support structure. The design rules that have led to the prototype design have been maintained but the implementation has been much improved. Also considerable improvement has been obtained with respect to the dynamic behavior. Accessibility and visibility on all parts and subsystems has changed such that everything is now clearly visible. Despite the increased performance no mass increase has been recorded meaning that more efficient use has been made of the material.
The active means to influence the segment shape by use of the warping harness has been completely redesigned. A very important quality that has been achieved is simplicity. Hence a minimum amount of components is used. Reliability and safety are other aspects that have been greatly improved compared to the prototypes. The design for the M1 segment support provides a solution that not only performs to specification but one that can be operated in a telescope environment, all 798 of them.
The High Efficiency and Resolution Multi Element Spectrograph, HERMES, is a facility-class optical spectrograph for the Anglo-Australian Telescope (AAT). It is designed primarily for Galactic Archaeology, the first major attempt to create a detailed understanding of galaxy formation and evolution by studying the history of our own galaxy, the Milky Way. The goal of the GALAH survey is to reconstruct the mass assembly history of the Milky Way through a detailed chemical abundance study of one million stars. The spectrograph is based at the AAT and is fed by the existing 2dF robotic fiber positioning system. The spectrograph uses volume phase holographic gratings to achieve a spectral resolving power of 28,000 in standard mode and also provides a high-resolution mode ranging between 40,000 and 50,000 using a slit mask. The GALAH survey requires an SNR greater than 100 for a star brightness of V=14 in an exposure time of one hour. The total spectral coverage of the four channels is about 100 nm between 370 and 1000 nm for up to 392 simultaneous targets within the 2-degree field of view. HERMES has been commissioned over three runs, during bright time in October, November, and December 2013, in parallel with the beginning of the GALAH pilot survey, which started in November 2013. We present the first-light results from the commissioning run and the beginning of the GALAH survey, including performance results such as throughput and resolution, as well as instrument reliability.
The High Efficiency and Resolution Multi Element Spectrograph, HERMES is an facility-class optical spectrograph for
the AAT. It is designed primarily for Galactic Archeology , the first major attempt to create a detailed
understanding of galaxy formation and evolution by studying the history of our own galaxy, the Milky Way. The goal of
the GALAH survey is to reconstruct the mass assembly history of the of the Milky Way, through a detailed spatially
tagged abundance study of one million stars. The spectrograph is based at the Anglo Australian Telescope (AAT) and is
fed by the existing 2dF robotic fiber positioning system. The spectrograph uses VPH-gratings to achieve a spectral
resolving power of 28,000 in standard mode and also provides a high-resolution mode ranging between 40,000 to 50,000
using a slit mask. The GALAH survey requires a SNR greater than 100 for a star brightness of V=14. The total spectral
coverage of the four channels is about 100nm between 370 and 1000nm for up to 392 simultaneous targets within the 2
degree field of view. Hermes has been commissioned over 3 runs, during bright time in October, November and
December 2013, in parallel with the beginning of the GALAH Pilot survey starting in November 2013. In this paper we
present the first-light results from the commissioning run and the beginning of the GALAH Survey, including
performance results such as throughput and resolution, as well as instrument reliability. We compare the abundance
calculations from the pilot survey to those in the literature.
The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical
Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for
high resolution ‘Galactic archaeology’ spectroscopy. The large clear aperture, the high diffraction efficiency, the line
frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new
metrology systems at the AAO to verify the performance of these VPH gratings.
The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor’s provided
data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post
The High Efficiency and Resolution Multi Element Spectrograph, HERMES is an optical spectrograph designed
primarily for the GALAH, Galactic Archeology Survey, the first major attempt to create a detailed understanding of
galaxy formation and evolution by studying the history of our own galaxy, the Milky Way1. The goal of the GALAH
survey is to reconstruct the mass assembly history of the of the Milky way, through a detailed spatially tagged
abundance study of one million stars in the Milky Way. The spectrograph will be based at the Anglo Australian
Telescope (AAT) and be fed with the existing 2dF robotic fibre positioning system. The spectrograph uses VPH-gratings
to achieve a spectral resolving power of 28,000 in standard mode and also provides a high resolution mode ranging
between 40,000 to 50,000 using a slit mask. The GALAH survey requires a SNR greater than 100 aiming for a star
brightness of V=14. The total spectral coverage of the four channels is about 100nm between 370 and 1000nm for up to
392 simultaneous targets within the 2 degree field of view.
Current efforts are focused on manufacturing and integration. The delivery date of spectrograph at the telescope is
scheduled for 2013. A performance prediction is presented and a complete overview of the status of the HERMES
spectrograph is given. This paper details the following specific topics:
The approach to AIT, the manufacturing and integration of the large mechanical frame, the opto-mechanical slit
assembly, collimator optics and cameras, VPH gratings, cryostats, fibre cable assembly, instrument control hardware and
software, data reduction.
The fiber instrument data simulator is an in-house software tool that simulates detector images of fiber-fed spectrographs
developed by the Australian Astronomical Observatory (AAO). In addition to helping validate the instrument designs,
the resulting simulated images are used to develop the required data reduction software. Example applications that have
benefited from the tool usage are the HERMES and SAMI instrumental projects for the Anglo-Australian Telescope
(AAT). Given the sophistication of these projects an end-to-end data simulator that accurately models the predicted
detector images is required. The data simulator encompasses all aspects of the transmission and optical aberrations of the
light path: from the science object, through the atmosphere, telescope, fibers, spectrograph and finally the camera
detectors. The simulator runs under a Linux environment that uses pre-calculated information derived from ZEMAX
models and processed data from MATLAB. In this paper, we discuss the aspects of the model, software, example
simulations and verification.
The Australian Astronomical Observatory (AAO) has recently completed a feasibility study for a fiber-positioner facility proposed for the Giant Magellan Telescope (GMT), called MANIFEST (the Many Instrument Fiber System). The MANIFEST instrument takes full advantage of the wide-field focal plane to efficiently feed other instruments. About 2000 individually deployable fiber units are envisaged, with a wide variety of aperture types (single-aperture, image- or pupil-slicing, IFU). MANIFEST allows (a) full use of the GMT's 20' field-of-view, (b) a multiplexed IFU capability, (c) greatly increased spectral resolution via image-slicing, (d) the possibility of OH-suppression in the near-infrared.
First light from the SAMI (Sydney-AAO Multi-object IFS) instrument at the Anglo-Australian Telescope (AAT) has
recently proven the viability of fibre hexabundles for multi-IFU spectroscopy. SAMI, which comprises 13 hexabundle
IFUs deployable over a 1 degree field-of-view, has recently begun science observations, and will target a survey of
several thousand galaxies. The scientific outputs from such galaxy surveys are strongly linked to survey size, leading the
push towards instruments with higher multiplex capability. We have begun work on a new instrument concept, called
Hector, which will target a spatially-resolved spectroscopic survey of up to one hundred thousand galaxies. The key
science questions for this instrument concept 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. One design option for Hector uses the existing 2 degree field-of view top end at the AAT, with 50 individual
robotically deployable 61-core hexabundle IFUs, and 3 fixed format spectrographs covering the visible wavelength range
with a spectral resolution of approximately 4000. A more ambitious option incorporates a modified top end at the AAT
with a new 3 degree field-of-view wide-field-corrector and 100 hexabundle IFUs feeding 6 spectrographs.
Following the successful commissioning of SAMI (Sydney-AAO Multi-object IFU) the AAO has undertaken concept
studies leading to a design of a new instrument for the AAT (Hector). It will use an automated robotic system for the
deployment of fibre hexabundles to the focal plane. We have analysed several concepts, which could be applied in the
design of new instruments or as a retrofit to existing positioning systems. We look at derivatives of Starbugs that could
handle a large fibre bundle as well as modifications to pick and place robots like 2dF or OzPoz. One concept uses large
magnetic buttons that adhere to a steel field plate with substantial force. To move them we replace the gripper with a
pneumatic device, which engages with the button and injects it with compressed air, thus forming a magnet preloaded air
bearing allowing virtually friction-less repositioning of the button by a gantry or an R-Theta robot. New fibre protection,
guiding and retraction systems are also described. These developments could open a practical avenue for the upgrade to a
number of instruments.
Starbugs are miniature piezoelectric 'walking' robots with the ability to simultaneously position many optical fibres
across a telescope's focal plane. Their simple design incorporates two piezoceramic tubes to form a pair of concentric
'legs' capable of taking individual steps of a few microns, yet with the capacity to move a payload several millimetres
per second. The Australian Astronomical Observatory has developed this technology to enable fast and accurate field
reconfigurations without the inherent limitations of more traditional positioning techniques, such as the 'pick and place'
robotic arm. We report on our recent successes in demonstrating Starbug technology, driven principally by R&D efforts
for the planned MANIFEST (many instrument fibre-system) facility for the Giant Magellan Telescope. Significant
performance gains have resulted from improvements to the Starbug system, including i) the use of a vacuum to attach
Starbugs to the underside of a transparent field plate, ii) optimisation of the control electronics, iii) a simplified
mechanical design with high sensitivity piezo actuators, and iv) the construction of a dedicated laboratory 'test rig'. A
method of reliably rotating Starbugs in steps of several arcminutes has also been devised, which integrates with the pre-existing
x-y movement directions and offers greater flexibility while positioning. We present measured performance data
from a prototype system of 10 Starbugs under full (closed-loop) control, at field plate angles of 0-90 degrees.
We report on the grating development for the High Efficiency and Resolution Multi Element Spectrograph (HERMES).
This paper discusses the challenges of designing, optimizing, and tolerancing large aperture volume phase holographic
(VPH) gratings for HERMES. The high spectral resolution requirements require steep angles of incidence, of 67.2
degrees, and high line densities, ranging between 2400 and 3800 lines per mm, resulting in VPH gratings that are highly
s-polarized that push the fabrication process to its limits.
We report on the technological achievements of our latest Starbug prototypes and their implications for smart focal plane
fiber positioning applications for wide-field astronomy. The Starbugs are innovative self-motile miniature robotic
devices that can simultaneously and independently position fibers or payloads over a field plate located at the telescope's
focal plane. The Starbugs concept overcomes many of the limitations associated with the traditional 'pick and place'
positioners where a robot places fixed buttons onto the field plate. The new Starbug prototypes use piezoelectric
actuators and have the following features: (i) new 'lift-and-step' method (discrete step) for accurate positioning over
different surfaces; and (ii) operate in an inverted hanging position underneath a transparent field plate, removing the need
for fibercable retractors. In this paper, we present aspects of the Starbug prototypes, including the theoretical model,
mechanical design, experimental setup, algorithms, performance and applications for astronomical instrumentation.
MANIFEST (the Many Instrument Fiber System) is a proposed fiber-positioner for the GMT, capable of feeding other
instruments as needed. It is a simple, flexible and modular design, based on the AAO's Starbugs, the University of
Sydney's Hexabundles, and extensive use of standard telecommunications fiber technology. Up to 2000 individually
deployable fiber units are envisaged, with a wide variety of aperture types (single-aperture, image-slicing, IFU).
MANIFEST allows (a) full use of the GMT's 20' field-of-view, (b) a multiplexed IFU capability, (c) greatly increased
spectral resolution via image-slicing, (d) efficient detector packing both spectrally and spatially, (e) the possibility of
OH-suppression in the near-infrared. Together, these gains make GMT the most powerful of the ELT's for wide-field
spectroscopy. It is intended that MANIFEST will form part of the GMT facility itself, available to any instrument able
to make use of it.
The AAO is building an optical high resolution multi-object spectrograph for the AAT for Galactic Archaeology. The
instrument has undergone significant design revision over that presented at the 2008 Marseilles SPIE meeting. The
current design is a 4-channel VPH-grating based spectrograph providing a nominal spectral resolving power of 28,000
and a high-resolution mode of 45,000 with the use of a slit mask. The total spectral coverage is about 1000 Angstroms
for up to 392 simultaneous targets within the 2 degree field of view. Major challenges in the design include the
mechanical stability, grating and dichroic efficiencies, and fibre slit relay implementation. An overview of the current
design and discussion of these challenges is presented.