One of the main goals of the European Solar Telescope (EST), a 4.2-m telescope, is to clarify the roots of the magnetic processes taking place in the solar atmosphere. This goal has a top-level requirement: perform simultaneous spectropolarimetric measurements in multiple spectral lines. For this purpose, EST will be equipped with a set of instruments working simultaneously in diverse spectral ranges. In this regard, we are designing a Coudé Light Distribution (CLD) responsible for delivering the incoming solar radiation to each instrument. The CLD is formed by a series of optical elements like dichroic and intensity beam splitters, flat mirrors, and optical compensators that will be interchangeable to offer the solar community maximum flexibility for performing observations. In developing the CLD, we are paying great attention to controlling aberration effects generated by the different elements that constitute the light distribution system. Also, we are defining the CLD to reach a balance between throughput, image quality, and a compact distribution of the instruments in the Coudé room. Our aim is to describe in this contribution the current design of the CLD. The present design constitutes the basis of the CLD, with enough flexibility to improve it in the future, if indeed, and adapt it to the evolution of other sub-systems like the instruments, the adaptive optics, or the telescope structure to guarantee that it fulfils the science requirements.
The European Solar Telescope (EST) aims to become the most ambitious ground-based solar telescope in Europe. Its roots lie in the knowledge and expertise gained from building and running previous infrastructures like, among others, the Vacuum Tower Telescope, Swedish Solar Telescope, or the GREGOR telescope. They are installed in the Canary Islands observatories, the selected EST site. Furthermore, the telescope has a novel optical design, including an adaptive secondary mirror (ASM) that allows reducing the number of optical surfaces to 6 mirrors (plus two lenses) before the instruments’ focal plane. The latter, combined with a configuration of mirrors that are located orthogonally oriented to compensate for the instrumental polarisation induced by each surface, makes EST a reference telescope in terms of throughput and polarimetric accuracy. In its main core design, EST also includes a Multi-Conjugated Adaptive Optics (MCAO) system where the ASM compensates for the ground layer turbulence. The rest of the mirrors on the optical train correct for the atmospheric turbulence at different layers of the atmosphere. The MCAO guarantees that the large theoretical spatial resolution of the 4-metre EST primary mirror is achieved over a circular FOV of 60 arcsec. Those main elements, combined with a set of instruments with capabilities for spectropolarimetry, make EST the next frontier in solar ground-based astronomy. In this contribution, we will cover the main properties and status of all the mentioned sub-systems and the following steps that will lead to the construction phase.
We describe the IR focal plane filters of the MAJIS imaging spectrometer for the JUICE mission to the Jupiter System. The focal plane filters provided by Viavi Solutions are integrated into a filter holder placed above the IR channel focal plane array, enclosed in a baffle and cooled to cryogenic temperatures. The filters comprise two segments bonded together on a sapphire substrate: a broad-band, low-pass filter and a narrow-band linear variable filter (LVF) in the MWIR. We present the justification for using such filters, their architecture, the measurement facilities that were implemented for assessing their performances and the derived optical performances. The filters have been fully qualified and integrated into MAJIS and are within the performance specifications.
We describe the IR focal plane unit of the MAJIS imaging spectrometer for the JUICE mission to the Jupiter Sys tem. Optical light from the telescope and spectrometer is focalized on the IR Focal plane unit which compris es a Teledyne Imaging Sensors H1RG detector overlain by a Viavi Solutions filter assembly. Both components are baffled and work at cryogenic temperatures. We describe the IR focal plane architecture, the measurement facilities and the main performance-critical specifications. The IR channel of MAJIS offers strong versatility with the capability to acquire high resolution spectra from the Jupiter atmosphere to organic matter on icy moon surfaces, over a wide spectral and dynamical range.
Text-based requirements management tools are widely used in engineering today. The concept behind it is quite simple, but this simplicity does not mean that these tools are affordable. In most cases, the cost of a requirements management tool license is similar to the cost of a CAD software license, the latter pertaining to a much more complex software tool. At cosmoBots.eu we have developed a plugin for a free and open project management tool (Redmine) that turns it into a powerful requirements management tool, including automatic and instant hierarchy and dependency diagrams, import/export from/to spreadsheets, full interoperability with other tools using the REST API, also including role-based lifecycle management and reporting. Several projects in IAC (EST, MICAL, NRT...) are officially using cosmoSys-Req to manage their requirements, and other projects or institutions (GTC, IACTEC...) are currently evaluating their use.
PLATO is an ESA mission to hunt for Earth-sized exoplanets in the habitable zone of their host star. The heart of the payload consists of 26 wide-field cameras. We develop a Common Electrical Ground Support Equipment (EGSE) framework for the testing and verification of these cameras. The focal planes are aligned to the telescope optics at ambient temperature and the performance verification is done at operational temperature in thermal-vacuum conditions in different facilities. The Common-EGSE system will guarantee that tests are executed via the same procedures and are analyzed identically, by providing a software framework that can be tuned for site-specific hardware and avoids duplicate developments. The Common EGSE provides commanding for the camera and the Ground Support Equipment (GSE), telemetry monitoring, logging, data storage, and data analysis. In addition, the design allows for sharing commanding and analysis scripts. We present the design of the system and the generic commanding scheme for test setup hardware.
The understanding of the solar outer atmosphere requires a simultaneous combination of imaging and spectral observations concerning the far UV lines that arise from the high chromospheres up to the corona. These observations must be performed with enough spectral, spatial and temporal resolution to reveal the small atmospheric structures and to resolve the solar dynamics. An Imaging Fourier Transform Spectrometer working in the far-UV (IFTSUV, Figure 1) is an attractive instrumental solution to fulfill these requirements. However, due to the short wavelength, to preserve IFTSUV spectral precision and Signal to Noise Ratio (SNR) requires a high optical surface quality and a very accurate (linear and angular) metrology to maintain the optical path difference (OPD) during the entire scanning process by: optical path difference sampling trigger; and dynamic alignment for tip/tilt compensation (Figure 2).
The Polarimetric and Helioseismic Imager (PHI) on board of Solar Orbiter will observe the Sun to measure the photospheric vector magnetic field and the line-of-sight velocity. It will employ a narrowband filtergraph (FG) to scan the FeI 6173 Å absorption line. At different spectral positions, the polarization state of the incoming light will be analyzed. The FG will provide a tuning range to scan the line, the continuum, and to compensate for the spacecraft radial velocity, as it will approach to the Sun down to 0.28 AU. The FG includes a Fabry-Perot etalon and two narrowband prefilters. The bandpass of the narrowest one has a nominal Full Width at Half Maximum (FWHM) of 2.7 Å. The measurement of the prefilters characteristics is essential for the instrument calibration. Here we present the results of the breadboard prefilters characterization, which is an important milestone in the development of the instrument.
The spectroscopy of the far UV emission lines of the solar spectrum combined with an imaging capability is essential to
understand the physics of the outer solar atmosphere. An imaging Fourier transform spectrometer (IFTSUV) is an
attractive instrumental solution to perform such far-UV solar observations. Working in the far UV involves high
precision metrology to maintain the optical path difference (OPD) during the entire scanning process of the
interferogram. It also involves a compact all-reflection design for UV applications. We present the specification of a
servo-system that enables dynamic tip/tilt alignment compensation and OPD sampling measurement of the IFTSUV
scanning mirror. We also discuss the first experimental results of a breadboard as well as the preliminary design of a
space-based device.
Imaging Fourier Transform Spectrometer working in the far UV (IFTSUV) may be the technical solution to
answer many unsolved problems concerning the physics of the solar outer atmosphere. The VUV domain
highly constrains the instruments design and performances as it demands a high optics surface quality and an
accurate metrology to preserve IFTSUV spectral precision and Signal to Noise Ratio (SNR). We present the
advancements on the specification of a metrology system, meeting the predicted performance requirements of
an IFTSUV.
The study of the outer solar atmosphere requires combining imaging and spectroscopy in the UV lines formed
in the high chromosphere, the transition region and the corona. We start from the science requirements and we
define the instrumental specifications in terms of field-of-view (FOV), spatial, temporal and spectral resolution
and bandpass. We propose two different all-reflection optical architectures based on interferometric techniques:
Spatial Heterodyne Spectroscopy (SHS); and Imaging Transform Spectrometer (IFTS). We describe the different
set-ups and compare the potential performances of the two types of solutions, and discuss their feasibility. We
conclude that IFTS appears to be the best solution, meeting the needs of UV solar physics. However, we point
out the many difficulties to be encountered, especially as far as metrology is concerned.
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