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 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.
The Low Order Wave Front Subsystem (LOWFS) provides field stabilization and low-order wave front sensing in seeing-limited and LTAO observing modes, measuring the motion of the instrument focal plane relative to the telescope wave front sensors. A new set of requirements have been set for the LOWFS, expecting the micron acquisition and submicron accuracy tracking of two objects in a 400mm technical field, instead of the previous set of requirements requiring just one.
A trade-off process has been conducted to explore different architecture options. This process starts with the selection of the trade-off main criteria and metrics that will drive the decision. Among those metrics there are performance and functionality requirements, impact on cost and schedule, among others. Additionally, weights are allocated for each one of the metrics. Then, brainstorms methods have been applied to analyze the different architectures without any preconcluded assessment on each solution. A preliminary selection of 2 solutions is done and the selected architectures are further developed. Finally, a trade-off matrix is filled by experts to obtain the selected architecture, which is developed further in this paper.
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 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 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. The Calibration Module (CM) is part of the HARMONI Instrument. It includes all the functionalities necessary to remove the instrumental signature from the observed science data, perform the technical calibrations needed to set up other sub-systems, and for monitoring the health of the instrument during operations. The CM is a complex and accurate optical configurable mechanism mainly composed by the following calibration units:
Integral Field Spectrograph Calibration Unit (ICU): It provides calibration for the integral field spectrograph. The ICU mimics the ELT pupil and F/# at the HARMONI entrance and provides with a set of illumination patterns by combining different light sources and focal plane masks.
Adaptive Optics Calibration Unit (AOCU): Intended for “Natural Guide Star Sensors (NGSS)” and “Laser Tomography Adaptive Optics (LTAO)” calibration.
Geometrical Calibration Unit (GCU): Using a well-known geometrical pattern of barely resolved point sources made of 480 optical fibers, this unit is intended for the NGSS guide probes.
In this paper, we present an overview of the CM design, describing its functional and optomechanical implementation.
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 can operate in three Adaptive Optics modes – SCAO, HCAO and LTAO - or with NOAO. The project is preparing for Final Design Reviews. The Pick-Off Arm (POA) module is part of the Low Order Wavefront Subsystem (LOWFS) which provides field stabilisation and low-order wavefront sensing in seeing-limited and LTAO observing modes, measuring the motion of the instrument focal plane relative to the telescope wavefront sensors. The POA module provides the source acquisition and tracking capabilities with 6 μm accuracy over a technical field of 400 mm (120 arcseconds) in diameter. The acquired beam is then reflected into the AO bench (LOB). A two-axis theta-phi architecture is proposed, with a large 600mm diameter “theta” axis carrying at its perimeter a small “phi” axis; the combined rotation of both therefore allowing a 300mm long periscope carried on the phi axis to position a Pick-Off Mirror anywhere within the full technical field. A flow-down of the main requirements is presented, describing the interaction between the different error contributors and the overall accuracy budget. Furthermore, we present the POA baseline design, together with the analysis of the technologies used within the POA different units. Finally, the prototype activities developed are also described with preliminary results of tests demonstrating the required positioning accuracy.
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.
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