HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. HARMONI is a work-horse instrument that provides efficient, spatially resolved spectroscopy of extended objects or crowded fields of view. The gigantic leap in sensitivity and spatial resolution that HARMONI at the ELT will enable promises to transform the landscape in observational astrophysics in the coming decade. The project has undergone some key changes to the leadership and management structure over the last two years. We present the salient elements of the project restructuring, and modifications to the technical specifications. The instrument design is very mature in the lead up to the final design review. In this paper, we provide an overview of the instrument's capabilities, details of recent technical changes during the red flag period, and an update of sensitivities.
Selected for the next generation of adaptive optics (AO) systems, the pyramid wavefront sensor (PWFS) is recognised for its closed AO loop performance. As new technologies are emerging, it is necessary to explore new methods to improve it. Microwave Kinetic Inductance Detectors (MKID) are photon-counting devices that measure the arrival time and energy of each incident photon, providing new capabilities over existing detectors and significant AO performance benefits. After developing a multi-wavelength PWFS simulation, we study the benefits of using an energy sensitive detector, analyse the PWFS performance according to wavelength and explore the possibility of using fainter natural guide stars by widening the bandpass of the wavefront sensor.
The Cassegrain U-Band Efficient Spectrograph (CUBES) is a high-efficiency spectrograph designed for observations from 305 to 400nm. It will be integrated at a Cassegrain focus of the Very Large Telescope (VLT). The image slicer technology is applied to reformat the field of view reducing the spectrograph entrance slit etendue and minimising the spectrograph volume and weight without slit losses. Two image slicers will provide CUBES with two spectral resolving powers: R≥20,000 for high resolution (HR) and R≥5,000 for low resolution (LR). Both image slicers are composed of two arrays of six spherical mirrors. For the HR mode, a rectangular field of view of 1.5arcsec by 10arcsec is reorganised into a slit of 0.19mm × 88mm; for the LR mode, a field of view of 6arcsec by 10arcsec is reformatted into a slit of 0.77mm × 88mm, with slicer mirrors of width 0.5mm and 2mm, respectively.
CUBES is currently in the Preliminary Design Phase (Phase B). This communication presents the Conceptual (Phase A) design and the main performance for the HR and LR image slicers addressing the following technological challenges: compact layout with the minimum number of optical components to optimise throughput, near diffraction limited optical quality, telecentric design with overlapped exit pupils for all slices of the field of view, distribution of the slicer mirrors to reduce shadows and selection of the best substrate for the very short wavelengths at which CUBES will operate.
HARMONI is the first light, adaptive optics assisted, integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope (ELT). A work-horse instrument, it provides the ELT’s diffraction limited spectroscopic capability across the near-infrared wavelength range. HARMONI will exploit the ELT’s unique combination of exquisite spatial resolution and enormous collecting area, enabling transformational science. The design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, and provide a summary of the instrument’s design. We also include recent changes to the project, both technical and programmatic, that have resulted from red-flag actions. Finally, we outline some of the simulated HARMONI observations currently being analyzed.
Microwave Kinetic Inductance Detectors (MKIDs) are beginning to become more prominent in astronomical instrumentation, due to their sensitivity, low noise, high pixel count for superconducting detectors, and inherent energy and time resolving capability. The Kinetic Inductance Detector Spectrometer (KIDSpec) will take advantage of these features, KIDSpec is a medium resolution MKID spectrograph for the optical/near infrared. KIDSpec will contribute to many science areas particularly those involving short and/or faint observations. When short period binary systems are found, typical CCD detectors will struggle to characterise these systems due to the very short exposures required, causing errors as large as the estimated parameter itself. The KIDSpec Simulator (KSIM) has been developed to investigate how much KIDSpec could improve on this. KIDSpec was simulated on an ELT class telescope to find the extent of its potential, and it was found that KIDSpec could observe a mV ≈ 24 with an SNR of 5 for a 10s exposure at 1420 spectral resolution. This would mean that KIDSpec on an ELT class telescope could spectroscopically follow up on any LSST photometric discoveries of LISA verification sources.
KEYWORDS: Signal processing, Sensors, Signal detection, Microwave radiation, Digital signal processing, Superconducting detectors, Single photon, Inductance, Image resolution, Field programmable gate arrays
This conference presentation was prepared for the X-Ray, Optical, and Infrared Detectors for Astronomy X conference at SPIE Astronomical Telescopes + Instrumentation, 2022.
HARMONI is the adaptive optics assisted, near-infrared and visible light integral field spectrograph for the Extremely Large Telescope (ELT). A first light instrument, it provides the work-horse spectroscopic capability for the ELT. As the project approaches its Final Design Review milestone, the design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, provide a summary of the instrument’s design, including plans for operations and calibrations, and provide a brief glimpse of the predicted performance for a specific observing scenario. The paper also provides some details of the consortium composition and its evolution since the project commenced in 2015.
This paper presents an analysis of the predicted performance of Microwave Kinetic Inductance Detectors (MKIDS) in interferometric instruments. MKIDS are energy sensitive photon counting detectors which can be designed to operate over a wide range of photon energies, and have excellent timing capabilities. Several Optical and near-IR (OIR) MKID instruments have already been used on-sky, and there are ongoing developments in the US and Europe to improve their capabilities for a wide range of science cases. For interferometric instruments the benefits are clear, with no read out noise or dark current, and time resolution of a microsecond, they can be used for both fringe tracking and science detectors. The inherent energy resolution allows for a range of potential improvements to instruments, from rejection of stray light and cosmic rays, to improved wavelength coverage, to simplified optical designs with few, or no, moving elements.
The High Angular Resolution Monolithic Optical and Near-infrared Integral field spectrograph (HARMONI) will be one of the instruments installed on ESO's 39-meter Extremely Large Telescope (ELT) at first light. The instrument will operate from 0.47 - 2.45 μm with Δλ/λ = 3,000 - 17,000. On-sky spatial pixels (spaxels) are divided between four spectrographs, each equipped with 11 transmission diffraction gratings to cover the ranges of wavelengths and spectral resolutions. These spectrographs will be cooled to ~140 K to decrease thermal radiation at longer wavelengths.
In all configurations, the diffraction grating will lose a greater fraction of scientific light than any other single optic in the instrument. Additionally, manufacturers are often unable to measure the fraction of transmitted light at HARMONI's longest wavelengths. For these reasons, we have developed a setup to measure the efficiencies of transmission diffraction gratings across HARMONI's bandpass. The setup uses modulated signals, a single detector, and a lock-in amplifier to minimize sources of systematic errors. A modified version of this setup may be used to measure stray light. These setups and initial results are presented.
HARMONI is an Integral Field Spectrograph (IFS) for ESO’s ELT. It has been selected as the first light spec- trograph and will provide the workhorse spectroscopic capabilities for the ELT for many years. HARMONI is currently at the PDR-level and the current design for the HARMONI IFS consists of a number of spaxel scales sampling down to the diffraction limit of the telescope. It uses a field splitter and image slicer to divide the field into 4 sub-units, each providing an input slit to one of four nearly identical spectrographs. All spectrographs will operate at near infrared wavelengths (0.81-2.45 micrometers), sampling different parts of the spectrum with a range of spectral resolving powers (3300, 7000, 18000). In addition, two of the four spectrographs will have a Visible capability (0.5-0.83 micrometers) operating with seeing-limited observations. This proceeding presents an overview of the opto-mechanical design and specifications of the spectrograph units for HARMONI.
HARMONI (High Angular Resolution MOnolithic Integral field spectrograph)1 is a planned first-light integral field spectrograph for the Extremely Large Telescope. The spectrograph sub-system is being designed, developed, and built by the University of Oxford. The project has just completed the Preliminary Design Review (PDR), with all major systems having nearly reached a final conceptual design. As part of the overall prototyping and assembly, integration, and testing (AIT) of the HARMONI spectrograph, we will be building a full-scale engineering model of the spectrograph. This will include all of the moving and mechanical systems, but without optics. Its main purpose is to confirm the AIT tasks before the availability of the optics, and the system will be tested at HARMONI cryogenic temperatures. By the time of the construction of the engineering model, all of the individual modules and mechanisms of the spectrograph will have been prototyped and cryogenically tested. The lessons learned from the engineering model will then be fed back into the overall design of the spectrograph modules ahead of their development.
Microwave Kinetic Inductance Detectors, or MKIDS, have the ability to simultaneous resolve the wavelength of individual photons and time tag photons with microsecond precision. This opens up a number of exciting new possibilities and efficiency gains for optical/IR astronomy. In this paper we describe a plan to take the MKID technology, which we have demonstrated on the Palomar, Lick, and Subaru Telescopes, out of the realm of private instruments usable only by experts. Our goal is to incorporate MKIDs into a facility-class instrument at the Keck 1 Telescope that can be used by a large part of the astronomical community. This new instrument, the Keck Radiometer Array using KID ENergy Sensors (KRAKENS), will be a 30 kpix integral field spectrograph (IFS) with a 42.5” x 45” field of view, extraordinarily wide wavelength coverage from 380-1350 nm, and a spectral resolution R=λ/▵λ > 20 at 400 nm. Future add on modules could enable polarimetry and higher spectral resolution. KRAKENS will be built using the same style MKID arrays, cryostat, and similar readout electronics to those used in the successful 10 kpix DARKNESS instrument at Palomar and 20 kpix MEC instrument at Subaru, significantly reducing the technical risk.
Two different cryogenic lens mounts have been developed and tested for potential use in the HARMONI spectrograph cameras. Problems were encountered during initial tests whereby the lenses were cracking where they were adhered to the mount. This was found to be caused by the choice of adhesive and solved by changing to a silicone RTV glue. The cryogenic performance of the two lens mount designs was tested, with the baseline design seeing the lens move by 18 μm radially from warm to cold, which is just within the tightest tolerances from the optical design, as long as any misalignments in the mounting procedure can be removed when aligning the lenses in the camera barrel. The alternative design was found have much worse performance with the lens moving by 40 μm due to fragile flexures and so is no longer being considered. A mounting procedure for spherical lenses has also been developed which is capable of peak to valley alignments of 10 μm axially, and 5 μm radially.
We show the results of a study into the performance of the E-ELT integral field spectrograph HARMONI for observations of galaxies at 2 < z < 4. Using the instrument simulation pipeline HSIM, we performed mock observations of galaxies in this redshift range using two different methods: (i) passive galaxies modeled with simple analytical spatial profiles and star formation histories; and (ii) a single z = 3 galaxy extracted from a high-resolution cosmological simulation, with a more complex and physically representative morphology and star formation history. We describe the software tools developed to convert the simulation data into a spectral cube containing the spatial and spectral properties of the galaxy’s light. From the mock observations we estimate how well the intrinsic properties of the galaxy can be recovered using commonly used analysis tools. The HSIM pipeline also allows us to study observational biases and their likely impact on the data. We discuss the implications of the project for the future science with HARMONI in the critical redshift regime for mass assembly in galaxies.
HARMONI is the E-ELT’s first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the E-ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers (R ~3500, 7500 and 20000) and instantaneous wavelength coverage spanning the 0.5 – 2.4 μm wavelength range of the instrument. In autumn 2015, the HARMONI project started the Preliminary Design Phase, following signature of the contract to design, build, test and commission the instrument, signed between the European Southern Observatory and the UK Science and Technology Facilities Council. Crucially, the contract also includes the preliminary design of the HARMONI Laser Tomographic Adaptive Optics system. The instrument’s technical specifications were finalized in the period leading up to contract signature. In this paper, we report on the first activity carried out during preliminary design, defining the baseline architecture for the system, and the trade-off studies leading up to the choice of baseline.
We present the details of a proposed microwave kinetic inductance detector (MKID) for the DAG (Eastern Anatolia Observatory in Turkish) telescope, DAG-MKID. The observatory will have a modern 4m size telescope that is currently under construction. Current plan to obtain the first light with the telescope is late 2019. The proposed MKID based instrument will enable astronomers to simultaneously detect photons in the relatively wide wavelength range of 4000 - 13500 Å with a timing accuracy of μs and spectral resolution R = ⋋/▵ ⋋ =10−25. With a planned field of view of approximately an arcminute, DAG-MKID will mostly be used for follow-up observations of transient or variable objects as well as a robust tool to measure photometric redshifts of a large number of galaxies or other extra-galactic objects.
The spectrograph sub-system is responsible for dispersing the light from the slicer with the required spectral resolving
power and imaging the spectra on to a detector. Each image slicer creates a single exit slit feeding a single spectrograph
unit containing visible (VIS) and infrared (IR) cameras. The four HARMONI slicers in total create four exit slits, feeding
four spectrograph units comprising of collimators, dispersers, and cameras. The focal plane of each camera contains a
mosaic of two 4Kx4K detectors, leading to 8K pixels along the length of the slit. The HARMONI wavelength range
(0.43 μm to 2.45 μm) splits into a visible and a near-infrared wavelength range with a transition wavelength at 0.8 μm. The optical design of HARMONI up to the dispersers is fully reflective and therefore the pre-optics and IFU subsystems,
as well the spectrograph collimator, can be used for both the visible and near-infrared wavelength range. Only
the dispersers and the spectrograph cameras are different for the visible and near infrared spectral ranges. To not
duplicate sub-systems unnecessarily the wavelength split in the spectrograph is realised by inserting a dichroic in the
collimated beam before the disperser to either direct the light towards the visible disperser and camera, or let it pass
toward the near-infrared disperser and camera. In contrast to the Phase A study all of HARMONI spectrograph unit will
have both visible and near infrared disperser and cameras.
We present here results of simulated integral field spectroscopic observations with the HARMONI instrument for the 39-m European Extremely Large Telescope. HARMONI (PI: N. Thatte) will provide adaptive optics- assisted 3D spectroscopy at a range of spatial scales and spectral resolutions. The instrument will for the first time allow the spectroscopic study of z = 2 - 5 galaxies at the scales of individual star-forming complexes
(∼100 pc). Using a sophisticated instrument simulator we show here innovative simulated observations of a
star-forming galaxy at z = 3, based on output from cosmological simulations using the RAMSES code. Our simulator includes realistic adaptive optics point spread functions, atmospheric and instrumental noise models
and observational parameters. Using these simulations, we can test analysis methods for the study of the galaxy’s dynamics and kinematics and compare these against predictions from galaxy evolution models. We thus demonstrate a methodology for predicting future observables from cosmological simulations.
HARMONI is a visible and near-infrared (0.47 to 2.45 μm) integral field spectrometer, providing the E-ELT's core
spectroscopic capability, over a range of resolving powers from R (≡λ/Δλ)~500 to R~20000. The instrument provides simultaneous spectra of ~32000 spaxels at visible and near-IR wavelengths, arranged in a √2:1 aspect ratio contiguous field. HARMONI is conceived as a workhorse instrument, addressing many of the E-ELT’s key science cases, and will
exploit the E-ELT's scientific potential in its early years, starting at first light. HARMONI provides a range of spatial
pixel (spaxel) scales and spectral resolving powers, which permit the user to optimally configure the instrument for a
wide range of science programs; from ultra-sensitive to diffraction limited, spatially resolved, physical (via morphology),
chemical (via abundances and line ratios) and kinematic (via line-of-sight velocities) studies of astrophysical sources.
Recently, the HARMONI design has undergone substantial changes due to significant modifications to the interface with
the telescope and the architecture of the E-ELT Nasmyth platform. We present an overview of the capabilities of
HARMONI, and of its design from a functional and performance viewpoint.
HARMONI is an integral field spectrograph working in the visible and near-infrared (0.47 to 2.45 μm) and will provide
the E-ELT’s core spectroscopic capability, starting at first light. To minimise the thermal background it will be a
cryogenic instrument with the optomechanics inside the cryostat having an operating temperature of 130K. We have
designed three different thermally compensating lens mounts and have started analysing their performance by measuring
the position of a glass blank relative to the mount to look for any displacement and tilt as it cooled down to operating
temperature. The suitability of a commercial iris shutter for use in HARMONI is also assessed and found to work down
to 120K, though further work is needed to prove it is reliable enough to be included in HARMONI, including an
accelerated lifetime test.
We present a novel concept for a highly sensitive, medium spectral resolution optical through near-IR spectrograph.
KIDSpec, the Kinetic Inductance Detector Spectrograph, uses the intrinsic energy resolving capability of an array of
optical/IR-sensitive MKIDs to distinguish multiple orders from a low line-density (echelle) grating. MKID arrays have a
wide bandpass (0.1-2.5um) and good quantum efficiency, making them strong candidates for replacing CCDs in many
astronomical instruments. By acting as an ‘order resolver’, the MKID array replaces the cross-disperser in an echelle
spectrograph. This greatly simplifies the optical layout of the spectrograph and enables longer slits than are possible with
cross-dispersed instruments. KIDSpec would have similar capabilities to ESO’s X-shooter instrument. It would provide
an R=4000-10,000 spectrum covering the entire optical and near-IR spectral range. In addition to a ‘long-slit’ mode, the
IFU would provide a small (~50 spaxel) field-of-view for spatially resolved sources. In addition, the photon-counting
operation of MKIDs and their photon-energy resolving ability enable a read-noise free spectrum with perfect cosmic ray
removal. The spectral resolution would be sufficient to remove the bright night-sky lines without the additional pixel
noise, making the instrument more sensitive than an equivalent semiconductor-based instrument.
KIDSpec would enhance many existing high-profile science cases, including transient (GRB, SNe, etc.) follow-up,
redshift determination of faint objects and transit spectroscopy of exoplanets. In addition it will enable unique science
cases, such as dynamical mass estimates of the compact objects in ultra-compact binaries.
Microwave Kinetic Inductance Detector (MKID) arrays, recently demonstrated at the Palomar 200 inch telescope, are a new superconducting detector technology that has great potential for astrophysics. We propose a new type of instrument, a Superconducting Multi-Object Spectrograph (SuperMOS), that uses MKIDs in conjunction with a focal plane mask. We present the design and science goals of a SuperMOS designed for LSST follow-up named Giga-z. Housing a 100,000 pixel MKID array with energy resolution R=50{100 and a 0.35-1.35 μm bandwidth, it will be capable of measuring 2 billion spectra and determining redshifts over 20,000 square degrees in 3 years down to mi ≈ 24.5 on a dedicated 4-meter telescope. Compared to LSST alone, Giga-z should improve the redshift precision by a factor of three with a much lower catastrophic failure rate.
Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology
due to their sensitivity and the ease with which they can be multiplexed into large arrays. An MKID is an energy
sensor based on a photon-variable superconducting inductance in a lithographed microresonator. It is capable
of functioning as both a photon detector across the electromagnetic spectrum and a particle detector. We have
recently demonstrated the world's first photon-counting, energy-resolving, ultraviolet, optical, and near infrared
MKID focal plane array in the ARCONS camera at the Palomar 200" telescope. Optical Lumped Element (OLE)
MKID arrays have significant advantages over semiconductor detectors such as charge coupled devices (CCDs).
They can count individual photons with essentially no false counts and determine the energy (to a few percent)
and arrival time (to ≈1μs) of every photon, with good quantum efficiency. Initial devices were degraded by
substrate events from photons passing through the Titanium Nitride (TiN) material of the resonator and being
absorbed in the substrate. Recent work has eliminated this issue, with a solution found to be increasing the
thickness of the TiN resonator from 20 to 60 nm.
ARCONS, the Array Camera for Optical to Near-infrared Spectrophotometry, was recently commissioned at the
Coude focus of the 200-inch Hale Telescope at the Palomar Observatory. At the heart of this unique instrument
is a 1024-pixel Microwave Kinetic Inductance Detector (MKID), exploiting the Kinetic Inductance effect to
measure the energy of the incoming photon to better than several percent. The ground-breaking instrument is
lens coupled with a pixel scale of 0.23"/pixel, with each pixel recording the arrival time (< 2 _μsec) and energy of
a photon (~10%) in the optical to near-IR (0.4-1.1 microns) range. The scientific objectives of the instrument
include the rapid follow-up and classi_cation of the transient phenomena
We report on the development of ARCONS, the ARray Camera for Optical to Near-IR Spectrophotometry.
This photon counting integral field unit (IFU), being built at UCSB and Caltech with detectors fabricated at
JPL, will use a unique, highly multiplexed low temperature detector technology known as Microwave Kinetic
Inductance Detectors (MKIDs). These detectors, which operate at 100 mK, should provide photon counting
with energy resolution of R = E/δE > 20 and time resolution of a microsecond, with a quantum efficiency of
around 50%. We expect to field the instrument at the Palomar 200" telescope in the first quarter of 2011 with
an array containing 1024 pixels in a 32×32 pixel form factor to yield a field of view of approximately 10×10
arcseconds. The bandwidth of the camera is limited by the rising sky count rate at longer wavelengths, but
we anticipate a bandwidth of 0.35 to 1.35 μm will be achievable. A simple optical path and compact dewar
utilizing a cryogen-free adiabatic demagnetization refridgerator (ADR) allows the camera to be deployed quickly
at Naysmith or Coud´e foci at a variety of telescopes. A highly expandable software defined radio (SDR) readout
that can scale up to much larger arrays has been developed.
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