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.
There is actual demand from astronomers for space instrumentation operating in the range of a few terahertz (between 1 and 10 THz) for deep space explorations. Analyzing this radiation coming from space is possible thanks to the development of a customized spectrometer, which splits the light collected at the terahertz spectral range using a diffraction grating. This diffraction grating has to be capable of withstanding the demanding conditions of space. However, obtaining the required dimensions, morphology, and wide spectral range for the grating is challenging. This work presents the outcomes of the diffraction efficiency verification for a metallic grating provided with a sawtooth profile and manufactured by laser micro-structuring with a 5-axis femtosecond laser system on an aluminum, fulfilling those requirements. The grating operates only with the first diffraction order (m=-1), favoring the transverse magnetic (TM) polarization over the transverse electric (TE) component, with a view to its incorporation in a polarization-selective optical system. In the course of the work, the grating characteristics, fabrication methods, and experimental verification of the grating properties, morphology, and diffraction efficiency will be presented. Diffraction efficiencies greater than 85% have been achieved.
ANSER Atmosphere (AT) is the second mission of INTA’s SmallSat constellation program. Its main objective is the study and monitoring of greenhouse gases, air quality and polar ozone by absorption spectroscopy. It is composed of a cluster of four CubeSats flying in formation, each of them comprised of 6U. The main payload of each CubeSat consists of a catadioptric telescope (1U) and a refractive spectrometer (2U) each of them working in a different spectral range from UV to SWIR. The optical design of the spectrometer, which spectrally disperses and analyses the energy collected by the telescope, is based on a reflective diffraction grating with a slit at the entrance. Due to the fact that this is an atmospheric observation mission and the precision required for the measurements, it is necessary to eliminate the polarization of the incoming light. For this reason, depolarizers have been included in the instrument design.
The design of a high-resolution multispectral spectrometer to measure atmospheric pollutants is presented. The spectrometer concept resolves a compact design with strict scientific requirements in a wide spectral range to be onboard in a CubeSat.
This paper describes the end-to-end opto-mechanical design of the SAFARI instrument on SPICA and the analysis of the spectrometer optical performances. SAFARI instrument is a high sensitivity grating-based spectrometer operating in the 34-230 μm wavelength range. The scientific drivers lead to the implementation of two modes of operation. The Low- Resolution (LR) or nominal mode (R~300) and the High-Resolution (HR), that implies to include a Martin-Puplett Fourier Transform Spectrometer (MP-FTS) to achieve the required spectral resolution (R~2000-11000). The optical system is all-reflective and consists of three main modules. The input optics module (IOM) is an unobscured reflective Offner relay. In the IOM a Beam Steering Mirror (BSM) is included for spatial modulation and to allow efficient sky mapping. The Band and Mode Distributing Optics (BMDO) module splits the radiation band into the four different spectral bands and includes the MP-FTS. The field image existing at the output of the BMDO constitutes the entrance to the Grating Module Optics (GM). These modules provide spectral dispersion by means of linear and reflective diffraction gratings and the final image onto the detectors. Performances of the GMs are high demanding with a detector divided into 2 sub-bands with a different pixel size for each sub-band.
SPICA provided the next step in mid- and far-infrared astronomical research and was a candidate of ESA's fifth medium class Cosmic Vision mission. SAFARI is one of the spectroscopic instruments on board SPICA. The Focal Plane Unit (FPU) design and analysis represent a challenge both from the mechanical and thermal point of view, as the instrument is working at cryogenic temperatures between 4.8K and 0.05K. Being a large instrument, with a current best estimate of 148,7kg of mass, its design will have to be optimized to fit within the mission´s mass and volume budget. The FPU will also have to be designed for its modularity and accessibility due to the large number of subsystems that SAFARI had to accommodate, highlighting Fourier Transform Spectrometer Mechanism (FTSM) and the three grating-based point source spectrometer modules (GM) which operates at 1.7K in the FPU, the latter representing 60% of the total mass of the instrument
The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments within the ESA’s ExoMars mission. The RLS instrument scientific goal consists of perform in-situ Raman spectroscopy over different organic and mineral powder samples of the Mars subsoil. It consists of three main units: SPU (Spectrometer Unit), iOH (Internal Optical Head), ICEU (Instrument Control and Excitation Unit) which are interconnected by an optical and electrical harnesses (OH and EH).
The SPU is one of the most critical units of the RLS instrument. The Engineering Qualification Model (EQM) unit has been already delivered after a proper qualified campaign in a very demanding environment with very restrictive design constraints, including Planetary Protection requirements. Also, a complete set of functional tests had been carried out under representative environment, simulating not only Mars rover´s laboratory conditions (thermal range and pressure), but also the cruise phase. Previously, an exhaustive qualification campaign was developed with two different purposes: to mitigate the risks associated to new optical elements included in the design and without space heritage; and to obtain a detailed comprehension of their behaviour under Mars conditions for facing the Flight Model (FM) optical design with guarantee of success.
EQM results were successful in terms of Engineering, and a SWaP-optimized system had been reached. The acquired knowledge of that model has been used to implement little improvements into SPU FM for acceptance. For operations, a big amelioration has been the reduction of the image ROI on the Charge-Coupled Device (CCD) after the improving of the alignment of the inclination degree of the image plane on CCD under the tightly integration constrains, letting to download the minimum necessary data bytes. These improvements achieved by a proper analysis of the image on the SPU CCD will allow to evaluate far better the Raman spectrum effects.
SPU FM Mechanical, Thermal-Vacuum campaign has been already finished in order to accept for flight the current unit which will be already completed and “flight qualified” at RLS system level before the congress. If everything continues on this way, the desired Technology Readiness level, TRL 8 maturity level, will be reported during the following text.
SAFARI is a point source spectrometer for the SPICA mission, which provides far-infrared spectroscopy and high sensitivity. SPICA mission, having a large cold telescope cooled to 6K above absolute zero, will provide an optimum environment where instruments are limited only by the cosmic background. SAFARI is a grating-based spectrometer with two modes of operation, Low Resolution (LR), or nominal mode (R~300) and High Resolution, (HR) (R~2000-11000). The SAFARI shall provide point source spectroscopy with diffraction-limited capability in four spectral bands over 34-230μm and a field of view (FoV) on sky over 2’×2’. Due to the complexity of the optical design of the SAFARI instrument a modular design was selected. Four principal modules are defined: Calibration Module (CS), Input Optics Module (IOM), Beam and Mode Distribution (BMDO) and Grating Modules (GMs). The present work is focused in the last module. Dispersive optical systems inherently demand the need of volume allocation for the optical system, being this fact somehow proportional to the wavelength and the required resolving power. The image sampling and the size of the detector elements are key drivers in this optical modular design. The optimization process has been performed taking into account the conceptual design parameters obtained during this phase such as collimator and camera optics focal lengths, subsystem diameters and periods and AOIs of the diffraction gratings.
The objective of this report is to present the study performed for a specially demanding solution of a spectrometer [1] design based on a transmissive holographic grating especially designed to actuate as the dispersion element. The main driver of the design has been to obtain a device with a clear reduction in mass, power and mechanical envelope with respect to the previous configuration based on a prism and/or Echelle grating. This simplification is produced mainly at expense of the waveband range. This study has been carried out by Laboratorio de Instrumentación Espacial (LINES) optical designers from Instituto Nacional de Técnica Aeroespacial (INTA).
Optical instrumentation on-board satellites suffer degradation due to the hostile conditions of space environment. Space conditions produce instrumentation performances changes causing a decrease or a cancellation of their features. Particularly, space environment conditions have a significant influence on the optical properties of glasses which are part of space optical systems.
Space environment characteristics which effects on the optical system have to be taken into account are: outgassing, volatile components, gas or water vapor which form part of the spacecraft materials, vacuum, microgravity, micrometeorites, space debris, thermal, mechanical and radiation environment and effects of the high atmosphere [1].
This work is focused on analyzing temperature variations and ultraviolet (UV) and gamma radiation effects on the optical properties of several glasses used on space applications.
Thermal environment is composed of radiation from the Sun, the albedo and the Earth radiation and the radiation from the spacecraft to deep space. Flux and influence of temperature on satellite materials depend on factors as the period of year or the position of them on the space system. Taking into account that the transfer mechanisms of heat are limited by the conduction and the radiation, high gradients of temperature are obtained in system elements which can cause changes of their optical properties, birefringence… Also, these thermal cycles can introduce mechanical loads into material structure due to the expansion and the contraction of the material leading to mechanical performances degradation [2].
However, it is the radiation environment the main cause of damage on optical properties of materials used on space instrumentation. This environment consists of a wide range of energetic particles between keV and MeV which are trapped by the geomagnetic field or are flux of particles that cross the Earth environment from the external of the Solar System [3].
The damage produced by the radiation environment on the optical materials can be classified in two types: ionizing or non-ionizing. This damage may produce continual or accumulative (dose) alterations on the optical material performances, or may produce alterations which not remain along the time (transitory effects). The effects of the radiation on optical materials can be summarized on changes of optical transmission and refractive index, variation of density and superficial degradation [4-6].
Two non-invasive and non-destructive techniques such as Optical Spectrum Analyzer and Spectroscopic Ellipsometry [7] have been used to characterize optically the three kinds of studied glasses, CaF2, Fused Silica and Clearceram.
The study of the temperature and radiation effects on the glasses optical properties showed that the gamma radiation is the principal responsible of glasses optical degradation. The optical properties of the Clearceram glass have been affected by the gamma irradiation due to the absorption bands induced by the radiation in the visible spectral range (color centers). Therefore, an analysis about the behavior of these color centers with the gamma radiation total dose and with the time after the irradiation has been carried out in the same way that it is performed in [8].
The Raman Laser Spectrometer is one of the ExoMars Pasteur Rover’s payload instruments that is devoted to the analytical analysis of the geochemistry content and elemental composition of the observed minerals provided by the Rover through Raman spectroscopy technique. One subsystem of the RLS instrument is the Internal Optical Head unit (IOH), which is responsible for focusing the light coming from the laser onto the mineral under analysis and for collecting the Raman signal emitted by the excited mineral. The IOH is composed by 4 commercial elements for Raman spectroscopy application; 2 optical filters provided by Iridian Spectral Technologies Company and 1 optical filter and 1 mirror provided by Semrock Company. They have been exposed to proton radiation in order to analyze their optical behaviour due to this hostile space condition. The proton irradiation test was performed following the protocol of LINES lab (INTA). The optical properties have been studied through transmittance, reflectance and optical density measurements, the final results and its influence on optical performances are presented.
SpicA FAR infrared Instrument, SAFARI, is one of the instruments planned for the SPICA mission. The SPICA
mission is the next great leap forward in space-based far-infrared astronomy and will study the evolution of galaxies,
stars and planetary systems. SPICA will utilize a deeply cooled 2.5m-class telescope, provided by European industry, to
realize zodiacal background limited performance, and high spatial resolution. The instrument SAFARI is a cryogenic
grating-based point source spectrometer working in the wavelength domain 34 to 230 μm, providing spectral resolving
power from 300 to at least 2000.
The instrument shall provide low and high resolution spectroscopy in four spectral bands. Low Resolution mode is the
native instrument mode, while the high Resolution mode is achieved by means of a Martin-Pupplet interferometer.
The optical system is all-reflective and consists of three main modules; an input optics module, followed by the Band
and Mode Distributing Optics and the grating Modules. The instrument utilizes Nyquist sampled filled linear arrays of
very sensitive TES detectors.
The work presented in this paper describes the optical design architecture and design concept compatible with the
current instrument performance and volume design drivers.
F. Rull, A. Sansano, E. Díaz, C. P. Canora, A. Moral, C. Tato, M. Colombo, T. Belenguer, M. Fernández, J. A. R. Manfredi, R. Canchal, B. Dávila, A. Jiménez, P. Gallego, S. Ibarmia, J. A. Prieto, A. Santiago, J. Pla, G. Ramos, C. Díaz, C. González
The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration
Programme, ExoMars mission.
ExoMars 2018 main Scientific objective is "Searching for evidence of past and present life on Mars".
Raman Spectroscopy is used to analyze the vibrational modes of a substance either in the solid, liquid or gas state. It
relies on the inelastic scattering (Raman Scattering) of monochromatic light produced by atoms and molecules. The
radiation-matter interaction results in the energy of the exciting photons to be shifted up or down. The shift in energy
appears as a spectral distribution and therefore provides an unique fingerprint by which the substances can be identified
and structurally analyzed.
The RLS is being developed by an European Consortium composed by Spanish, French, German and UK partners. It will
perform Raman spectroscopy on crushed powdered samples inside the Rover's Analytical Laboratory Drawer.
Instrument performances are being evaluated by means of simulation tools and development of an instrument prototype.
F. Rull, A. Sansano, E. Díaz, M. Colombo, T. Belenguer, M. Fernández, V. Guembe, R. Canchal, B. Dávila, A. Sánchez, H. Laguna, G. Ramos, C. González, D. Fraga, P. Gallego, I. Hutchinson, R. Ingley, J. Sánchez, C. Canora, A. Moral, S. Ibarmia, J. A. Prieto, J. A. R. Manfredi, P. Cabo, C. Díaz, A. Jiménez, J. Pla, R. Margoillés
The Raman Laser Spectrometer instrument is included in ExoMars program Pasteur payload and it is focused on the
Mars samples analytical analysis of the geochemistry content and elemental composition of the observed crushed
samples obtained by the Rover.
One of the most critical Units of the RLS is the Spectrometer unit (SPU) that performs Raman spectroscopy technique
and operates in a very demanding environment (operative temperature: from -40 ºC to 6 ºC) with very restrictive design
constraints. It is a very small optical instrument capable to cope with 0.09 nm/pixel of resolution. The selected solution is
based on a single transmisive holographic grating.
At this stage of the project SPU Team is preparing the Conceptual Design Review that will take place at the end of
October 2011.
F. Rull, A. Sansano, E. Díaz, C. Canora, A. Moral, C. Tato, M. Colombo, T. Belenguer, M. Fernández, J. A. Manfredi, R. Canchal, B. Dávila, A. Jiménez, P. Gallego, S. Ibarmia, J. A. Prieto, A. Santiago, J. Pla, G. Ramos, C. González
The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration
Programme, ExoMars mission.
The RLS Instrument will perform Raman spectroscopy on crushed powered samples deposited on a small container after
crushing the cores obtained by the Rover's drill system. This is the first time that a Raman spectrometer will be launched
in an out planetary mission.
The Instrument will be accommodated and operate inside the Rover's ALD (Analytical Laboratory Drawer), complying
with COSPAR (Committee on Space Research) Planetary Protection requirements.
The RLS Instrument is composed by the following units: SPU (Spectrometer Unit); iOH: (Internal Optical Head); ICEU (Instrument Control and Excitation Unit).
Other instrument units are EH (Electrical Harness), OH (Optical Harness) and RLS SW On-Board.
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