| 1. |
- Carlomagno, Brunella, et al.
(författare)
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Mid-IR AGPMs for ELT applications
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- The mid-infrared region is well suited for exoplanet detection thanks to the reduced contrast between the planet and its host star with respect to the visible and near-infrared wavelength regimes. This contrast may be further improved with Vector Vortex Coronagraphs (VVCs), which allow us to cancel the starlight. One flavour of the VVC is the AGPM (Annular Groove Phase Mask), which adds the interesting properties of subwavelength gratings (achromaticity, robustness) to the already known properties of the VVC. In this paper, we present the optimized designs, as well as the expected performances of mid-IR AGPMs etched onto synthetic diamond substrates, which are considered for the E-ELT/METIS instrument.
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| 2. |
- de Jong, Roelof S., et al.
(författare)
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4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
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Konferensbidrag (refereegranskat)abstract
- 4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].
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| 3. |
- Delacroix, Christian, et al.
(författare)
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Development of a subwavelength grating vortex coronagraph of topological charge 4 (SGVC4)
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- One possible solution to achieve high contrast direct imaging at a small inner working angle (IWA) is to use a vector vortex coronagraph (VVC), which provides a continuous helical phase ramp in the focal plane of the telescope with a phase singularity in its center. Such an optical vortex is characterized by its topological charge, i.e., the number of times the phase accumulates 2 pi radians along a closed path surrounding the singularity. Over the past few years, we have been developing a charge-2 VVC induced by rotationally symmetric subwavelength gratings (SGVC2), also known as the Annular Groove Phase Mask (AGPM). Since 2013, several SGVC2s (or AGPMs) were manufactured using synthetic diamond substrate, then validated on dedicated optical benches, and installed on 10-m class telescopes. Increasing the topological charge seems however mandatory for cancelling the light of bright stars which will be partially resolved by future Extremely Large Telescopes in the near-infrared. In this paper, we first detail our motivations for developing an SGVC4 (charge 4) dedicated to the near-infrared domain. The challenge lies in the design of the pattern which is unrealistic in the theoretically perfect case, due to state-of-the-art manufacturing limitations. Hence, we propose a new realistic design of SGVC4 with minimized discontinuities and optimized phase ramp, showing conclusive improvements over previous works in this field. A preliminary validation of our concept is given based on RCWA simulations, while full 3D finite-difference time-domain simulations (and eventually laboratory tests) will be required for a final validation.
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| 4. |
- Follert, R., et al.
(författare)
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CRIRES plus : a cross-dispersed high-resolution infrared spectrograph for the ESO VLT
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- High-resolution infrared spectroscopy plays an important role in astrophysics from the search for exoplanets to cosmology. Yet, many existing infrared spectrographs are limited by a rather small simultaneous wavelength coverage. The AO assisted CRIRES instrument, installed at the ESO VLT on Paranal, is one of the few IR (0.92-5.2 mu m) high-resolution spectrographs in operation since 2006. However it has a limitation that hampers its efficient use: the wavelength range covered in a single exposure is limited to similar to 15 nanometers. The CRIRES Upgrade project (CRIRES+) will transform CRIRES into a cross-dispersed spectrograph and will also add new capabilities. By introducing cross-dispersion elements the simultaneously covered wavelength range will be increased by at least a factor of 10 with respect to the present configuration, while the operational wavelength range will be preserved. For advanced wavelength calibration, new custom made absorption gas cells and etalons will be added. A spectro-polarimetric unit will allow one for the first time to record circularly polarized spectra at the highest spectral resolution. This will be all supported by a new data reduction software which will allow the community to take full advantage of the new capabilities of CRIRES+.
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| 5. |
- Lizon, Jean Louis, et al.
(författare)
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Opto-mechanical design of a new Cross Dispersion Unit for the CRIRES plus high resolution spectrograph for the VLT
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
-
Konferensbidrag (refereegranskat)abstract
- CRIRES is one of the few IR (0.92-5.2 mu m) high-resolution spectrographs in operation at the VLT since 2006. Despite good performance it suffers a limitation that significantly hampers its ability: a small spectral coverage per exposure. The CRIRES upgrade (CRIRES+) proposes to transform CRIRES into a cross-dispersed spectrograph while maintaining the high resolution (100000) and increasing the wavelength coverage by a factor 10 compared to the current capabilities. A major part of the upgrade is the exchange of the actual cryogenic pre-disperser module by a new cross disperser unit. In addition to a completely new optical design, a number of important changes are required on key components and functions like the slit unit and detectors units. We will outline the design of these new units fitting inside a predefined and restricted space. The mechanical design of the new functions including a description and analysis will be presented. Finally we will present the strategy for the implementation of the changes.
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| 6. |
- Lockhart, Matthew, et al.
(författare)
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Novel infrared polarimeter for the ESO CRIRES plus instrument
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- The CRIRES infrared spectrograph at the European Southern Observatory (ESO) Very Large Telescope (VLT) facility will soon receive an upgrade. This upgrade will include the addition of a module for performing high-resolution spectropolarimetry. The polarimetry module will incorporate a novel infrared beamsplitter based on polarization gratings (PGs). The beamsplitter produces a pair of infrared output beams, with opposite circular polarizations, which are then fed into the spectrograph. Visible light passes through the module virtually unaltered and is then available for use by the CRIRES adaptive optics system. We present the design of the polarimetry module and measurements of PG behavior in the 1 to 2.7 mu m wavelength range.
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| 7. |
- Oliva, E., et al.
(författare)
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Concept and optical design of the cross-disperser module for CRIRES
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- CRIRES, the ESO high resolution infrared spectrometer, is a unique instrument which allows astronomers to access a parameter space which up to now was largely uncharted. In its current setup, it consists of a single-order spectrograph providing long-slit, single-order spectroscopy with resolving power up to R=100,000 over a quite narrow spectral range. This has resulted in sub-optimal efficiency and use of telescope time for all the scientific programs requiring broad spectral coverage of compact objects (e.g. chemical abundances of stars and intergalactic medium, search and characterization of extra-solar planets). To overcome these limitations, a consortium was set-up for upgrading CRIRES to a cross-dispersed spectrometer, called CRIRES+. This paper presents the updated optical design of the cross-dispersion module for CRIRES+. This new module can be mounted in place of the current pre-disperser unit. The new system yields a factor of >10 increase in simultaneous spectral coverage and maintains a quite long slit (10"), ideal for observations of extended sources and for precise sky-background subtraction.
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| 8. |
- Seemann, U., et al.
(författare)
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Wavelength calibration from 1-5 mu m for the CRIRES plus high-resolution spectrograph at the VLT
- 2014
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Ingår i: GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V. - : SPIE. - 9780819496157
-
Konferensbidrag (refereegranskat)abstract
- CRIRES at the VLT is one of the few adaptive optics enabled instruments that offer a resolving power of 10 5 from 1 - 5 mu m. An instrument upgrade (CRIRES+) is proposed to implement cross-dispersion capabilities, spectro-polarimetry modes, a new detector mosaic, and a new gas absorption cell. CRIRES+ will boost the simultaneous wavelength coverage of the current instrument (similar to lambda/70 in a single-order) by a factor of greater than or similar to 10 in the cross-dispersed configuration, while still retaining a 10 arcsec slit suitable for long-slit spectroscopy. CRIRES+ dramatically enhances the instrument's observing efficiency, and opens new scientific opportunities. These include high-precision radial-velocity studies on the 3m/s level to characterize extra-solar planets and their athmospheres, which demand for specialized, highly accurate wavelength calibration techniques. In this paper, we present a newly developed absorption gas-cell to enable high-precision wavelength calibration for CRIRES+. We also discuss the strategies and developments to cover the full operational spectral range (1-5 mu m), employing hollow-cathode emission lamps, Fabry-Perot etalons, and absorption gas-cells.
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| 9. |
- Zerbi, F. M., et al.
(författare)
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HIRES : The High Resolution Spectrograph for E-ELT
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- The current instrumentation plan for the E-ELT foresees a High Resolution Spectrograph conventionally indicated as HIRES. Shaped on the study of extra-solar planet atmospheres, Pop-III stars and fundamental physical constants, HIRES is intended to embed observing modes at high-resolution (up to R=150000) and large spectral range (from the blue limit to the K band) useful for a large suite of science cases that can exclusively be tackled by the E-ELT. We present in this paper the solution for HIRES envisaged by the "HIRES initiative", the international collaboration established in 2013 to pursue a HIRES on E-ELT.
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