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.
HARMONI is the first light visible and near-IR integral field spectrograph for the Extremely Large Telescope. It covers a large spectral range from 470nm to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes (including a High Contrast capability) - or with Non Adaptive Optics. The project is preparing for Final Design Reviews. In this paper, we present the optical design of the Pre-Optics for Final Design Reviews, the pre-optics take light entering the science cryostat (from the telescope or calibration system), reformatting and conditioning to be suitable for input for the rest of the instrument. This involves many functions, mainly relaying the light from the telescope focal plane to the integral field unit focal plane via a set of interchangeable scale changing optics. The pre-optics also provides components including a focal plane mask wheel, cold pupil masks, spectral order sorting filters, a fast shutter, and a pupil imaging capability to check telescope/instrument pupil alignment.
The Gran Telescopio de Canarias Adaptive Optic System (GTCAO) is built to provide nearly diffraction-limited images to GTC. GRANCAIN (GRAN CAmara INfrarroja) is the first light cryogenic imaging instrument in J, H, and K infrared bands, which will be integrated into the Nasmyth focus of GTCAO. The instrument is designed to image the NIR (NearInfrared) diffraction limit for a field of view of 22x22 arcsec operating up to conditions of 1.5 arcsec and zenithal distances up to 60 deg. The instrument has a telecentric optical design based on a collimator camera with a 2:1 magnification, with a cold stop, and the filters between with an infrared detector everything inside the cryostat for operating at 50 K. This article presents a comprehensive overview of the end-to-end optical design of GRANCAIN. It explores the selection criteria for diverse commercial elements, conducts thermal analysis utilizing Ansys Zemax OpticStudio, and delineates the acceptance tests performed at the IAC. The article also encompasses tolerance analysis using Ansys Zemax OpticStudio and establishing the error budget. Furthermore, the text provides a detailed account of the alignment process, achieved through the mechanical positioning of each optical element with a laser tracker and the confirmation of positions under cryogenic conditions is conducted using an alignment telescope. Lastly, the article discusses the optical acceptance plans for the instrument before its integration into GTCAO.
This paper introduces a new technique for performing binary adaptive optics using optical components only, without the help of any electronic, or optoelectronic device. In this technique, the interferogram produced by the interference of a reference plane wave and the distorted wave modulates a light-driven crystal. The modulated light-driven crystal may produce pupil-plane only-phase or only-amplitude binary masks to mitigate phase aberrations. This new setup is more energy efficient and keeps the previous advantages as the capability of working unsupported. These features make it suitable for applications in hard-to-reach or hazardous locations such as satellites, underwater or contaminated places. The paper includes a simple experimental validation.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It will use an image slicer to provide spectra over a single contiguous area, providing fields of view on the sky of 9.3x6.3”, 4.2x3.1”, 2.1x1.5” and 0.84x0.62” with increasing spatial resolution (i.e.- 60x30, 20x20, 10x10 and 4x4 mas2) and magnification 2, 3/6, 6/12 and 15/30 respectively. The anamorphic magnifications in 20x20, 10x10 and 4x4 scales are implemented using two toroidal mirrors in each optical path. In this paper, we present a complete tolerance analysis for the anamorphic stages and a compensation procedure to ensure the requirements of the system.
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.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. The pre-optics take light entering the science cryostat (from the telescope or calibration system), reformatting and conditioning to be suitable for input for the rest of the instrument. In this paper, we present a complete stray light analysis of the HARMONI pre-optics including scattering from optical surface roughness and coatings, unwanted light from mechanical mounts and mechanisms, ghost reflections and scattering from particulate contaminants. Several solutions to reduce this unwanted light are proposed.
HARMONI, an adaptive optics (AO) assisted integral field spectrograph (IFS), will be the core spectroscopic capability for the European Southern Observatory’s (ESO’s) Extremely Large Telescope (ELT). It will support several AO modes and achieve diffraction-limited (≈10 mas) to seeing-limited spatial resolution, at low to high spectral resolving powers (λ/Δλ = 3,000-18,000) spanning the visible to near-infrared wavelength range (0.46-2.45 μm). In this paper we describe the modelling of the entire optical science path, from the creation of the end-to-end optical model, over how we analyse the optical performance, to the preliminary results of both nominal and as-built Monte-Carlo instances of HARMONI.
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.
HARMONI is a visible and near-infrared (0.5 to 2.45 μm) integral field spectrograph, providing the E-ELT's core spectroscopic capability, over a range of resolving powers from R (λ/Δλ) ~ 3500 to ~18000. The instrument provides simultaneous spectra of ∼32000 spaxels arranged in a sqrt(2):1 aspect ratio contiguous field. The pre-optics take light entering the science cryostat (from the telescope or calibration system), reformatting and conditioning to be suitable for input for the rest of the instrument. This involves many functions, mainly relaying the light from the telescope focal plane to the integral field unit (IFU) focal plane via a set of interchangeable scale changing optics. The pre-optics also provides components including a focal plane mask wheel, cold pupil masks, spectral order sorting filters, a fast shutter, and a pupil imaging capability to check telescope/instrument pupil alignment. In this paper, we present the optical design of the HARMONI pre-optics at Preliminary Design Review and, in particular, we detail the differences with the previous design and the difficulties salved to the Preliminary Design Review.
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.
A new technique for high resolution wavefront sensing has been introduced. It is based on the Optical Differentiation
wavefront sensor, however its application has required the development of a diffractive element that provides four or
five copies of the original wavefront. It some aspect the result is similar to that provide by the Pyramid sensor although
from a theoretical point of view is more close to the Modified Hartmann sensor. Here we introduce the theoretical
background and principles along with an example of phase derivative estimate based on a computer simulation. The
technique looks very promising since it is simple, with high resolution, without moving parts and allows us an easy post
processing to recover Zernike coefficients. Nevertheless, a lot of work has to be completed to a proper evaluation of its
actual capabilities, noise, resolution, etc.
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