The Sentinel-4 mission (S4) is part of the Global Monitoring for Environment and Security (GMES) initiative and covers the needs for continuous monitoring of Earth atmospheric composition and air pollution [1].

In the frame of ESA‘s earth-observation program “Copernicus”, the Fraunhofer IOF develops for the Sentinel-4/UVN spectrometer, the optical gratings for the near-infrared spectral channel together with its isostatic mounts.

Dark matter and dark energy mysteries will be explored by the Euclid ESA M-class space mission which will be launched in 2020. Millions of galaxies will be surveyed through visible imagery and NIR imagery and spectroscopy in order to map in three dimensions the Universe at different evolution stages over the past 10 billion years. The massive NIR spectroscopic survey will be done efficiently by the NISP instrument thanks to the use of grisms (for “Grating pRISMs”) developed under the responsibility of the LAM. In this paper, we present the verification philosophy applied to test and validate each grism before the delivery to the project. The test sequence covers a large set of verifications: optical tests to validate efficiency and WFE of the component, mechanical tests to validate the robustness to vibration, thermal tests to validate its behavior in cryogenic environment and a complete metrology of the assembled component. We show the test results obtained on the first grism Engineering and Qualification Model (EQM) which will be delivered to the NISP project in fall 2016.

By uniting a grating with a prism to a GRISM compound, the optical characteristics of diffractive and refractive elements can be favorably combined to achieve outstanding spectral resolution features. Ruling the grating structure into the prism surface is common for wavelengths around 1 μm and beyond, while adhesive bonding of two separate parts is generally used for shorter wavelengths and finer structures. We report on a manufacturing approach for joining the corresponding glass elements by the technology of hydrophilic direct bonding. This allows to manufacture the individual parts separately and subsequently combine them quasimonolithically by generating stiff and durable bonds of vanishing thickness, high strength and excellent transmission. With this approach for GRISM bonding, standard direct-write- or mask-lithography equipment may be used for the fabrication of the grating structure and the drawbacks of adhesive bonding (thermal mismatch, creep, aging) are avoided. The technology of hydrophilic bonding originates from “classical” optical contacting [1], but has been much improved and perfected during the last decades in the context of 3-dimensinal stacking Si-wafers for microelectronic applications [2]. It provides joins through covalent bonds of the Si-O-Si type at the nanometer scale, i.e. the elementary bond type in many minerals and glasses. The mineral nature of the bond is perfectly adapted to most optical materials and the extremely thin bonding layers generated with this technology are well suited for transmission optics. Creeping under mechanical load, as commonly observed with adhesive bonding, is not an issue. With respect to diffusion bonding, which operates at rather high temperatures close to the glass transition or crystal melting point, hydrophilic bonding is a low temperature process that needs only moderate heating. This facilitates provision of handling and alignment means for the individual parts during the set-up stages and greatly eases joining optical materials of different thermal expansion. The technology has been successfully used in the past for bonding various glasses as well as crystalline optical materials [3, 4]. Here we will focus on bonding prisms elements and binary gratings of fused silica with and without coatings at the bonding interface. Further, preliminary results on bonding prism-grating-prism (PGP) combinations will be presented.

The use of Bidirectional Scatter Distribution Function (BSDF) in space industry and especially when designing telescopes is a key feature. Indeed when speaking about space industry, one can immediately think about stray light issues. Those important phenomena are directly linked to light scattering. Standard BSDF measurement goniophotometers often have a resolution of about 0.1° and are mainly working in or close to the visible spectrum. This resolution is far too loose to characterize ultra-polished surfaces. Besides, wavelength range of BSDF measurements for space projects needs to be done far from visible range. How can we measure BSDF of ultra-polished surfaces and diffraction gratings in the UV and IR range with high resolution? We worked on developing a new goniophometer bench in order to be able to characterize scattering of ultra-polished surfaces and diffraction gratings used in everyday space applications. This ten meters long bench was developed using a collimated beam approach as opposed to goniophotometer using focused beam. Sources used for IR characterization were CO2 (10.6?m) and Helium Neon (3.39?m) lasers. Regarding UV sources, a collimated and spatially filtered UV LED was used. The detection was ensure by a photomultiplier coupled with synchronous detection as well as a MCT InSb detector. The so-built BSDF measurement instrument allowed us to measure BSDF of ultra-polished surfaces as well as diffraction gratings with an angular resolution of 0.02° and a dynamic of 1013 in the visible range. In IR as well as in UV we manage to get 109 with same angular resolution of 0.02°. The 1m arm and translation stages allows us to measure samples up to 200mm. Thanks to such a device allowing ultra-polished materials as well as diffraction gratings scattering characterization, it is possible to implement those BSDF measurements into simulation software and predict stray light issues. This is a big help for space industry engineers to apprehend stray light due to surface finishes and to delete those effects before the whole project is done. We are now thinking of possible improvement on our optical bench to try to get dynamic in IR and UV similar to what we have in visible range (e.g. 1013).

An Immersion grating is a powerful optical device for the infrared high-resolution spectroscope. We already fabricated the large CdZnTe(CZT) immersion grating (Sukegawa et al. (2012), Fig.1)[1][2][3] and Germanium(Ge) immersion grating (Sukegawa et al. (2015), Fig.2)[4]. Ge is the best material for a mid-infrared immersion grating because of Ge has very large reflective index (n=4.0).

Gratings are the core element of the spectrometer. For imaging spectrometers beside the polarization sensitivity and efficiency the imaging quality of the diffraction grating is essential. Lenses and mirrors can be produced with lowest wavefront aberrations. Low aberration imaging quality of the grating is required not to limit the overall imaging quality of the instrument. Different types of spectrometers will lead to different requirements on the wavefront aberrations for their specific diffraction gratings. The wavefront aberration of an optical grating is a combination of the substrate wavefront and the grating wavefront. During the manufacturing process of the grating substrate different processes can be applied in order to minimize the wavefront aberrations. The imaging performance of the grating is also optimized due to the recording setup of the holography.

This technology of holographically manufactured gratings is used for transmission and reflection gratings on different types of substrates like prisms, convex and concave spherical and aspherical surface shapes, free-form elements. All the manufactured gratings are monolithic and can be coated with high reflection and anti-reflection coatings. Prism substrates were used to manufacture monolithic GRISM elements for the UV to IR spectral range preferably working in transmission. Besides of transmission gratings, numerous spectrometer setups (e.g. Offner, Rowland circle, Czerny-Turner system layout) working on the optical design principles of reflection gratings. The present approach can be applied to manufacture high quality reflection gratings for the EUV to the IR.

In this paper we report our latest results on manufacturing lowest wavefront aberration gratings based on holographic processes in order to enable at least diffraction limited complex spectrometric setups over certain wavelength ranges. Beside the results of low aberration gratings the latest achievements on improving efficiency together with less polarization sensitivity of diffractive gratings will be shown for different grating profiles.

For an imaging spectrometer, the changing polarization properties of the incoming beam is a performance limiting factor. Indeed, while it is impossible to know in advance what the polarization state of the beam will be, the efficiency of the grating varies with it.

Ingenio/SEOSAT is a multi-spectral high-resolution optical satellite for Earth remote sensing, designed to provide imagery to different Spanish civil, institutional and governmental users, and potentially to other European users in the frame of GMES and GEOSS.

The Colour and Stereo Surface Imaging System (CaSSIS) camera was launched on 14 March 2016 onboard the ExoMars Trace Gas Orbiter (TGO) and it is currently in cruise to Mars.

The CaSSIS high resolution optical system is based on a TMA telescope (Three Mirrors Anastigmatic configuration) with a 4th powered folding mirror compacting the CFRP (Carbon Fiber Reinforced Polymer) structure. The camera EPD (Entrance Pupil Diameter) is 135 mm and the focal length is 880 mm, giving an F# 6.5 system; the wavelength range covered by the instrument is 400-1100 nm. The optical system is designed to have distortion of less than 2%, and a worst case Modulation Transfer Function (MTF) of 0.3 at the detector Nyquist spatial frequency (i.e. 50 lp/mm).

The Focal Plane Assembly (FPA), including the detector, is a spare from the Simbio-Sys instrument of the Italian Space Agency (ASI). Simbio-Sys will fly on ESA’s BepiColombo mission to Mercury in 2018. The detector, developed by Raytheon Vision Systems, is a 2k×2k hybrid Si-PIN array with 10 μm-pixel pitch. The detector allows snap shot operation at a read-out rate of 5 Mpx/s with 14-bit resolution. CaSSIS will operate in a push-frame mode with a Filter Strip Assembly (FSA), placed directly above the detector sensitive area, selecting 4 colour bands. The scale at a slant angle of 4.6 m/px from the nominal orbit is foreseen to produce frames of 9.4 km × 6.3 km on the Martian surface, and covering a Field of View (FoV) of 1.33° cross track × 0.88° along track.

The University of Bern was in charge of the full instrument integration as well as the characterisation of the focal plane of CaSSIS. The paper will present an overview of CaSSIS and the optical performance of the telescope and the FPA. The preliminary results of the on-ground calibration campaign and the first light obtained during the commissioning and pointing campaign (April 2016) will be described in detail. The instrument is acquiring images with an average Point Spread Function at Full-Width-Half-Maximum (PSF FWHM) of < 1.5 px, as expected.

Copernicus is a European Union (EU) led initiative designed to establish a European capacity for the provision and use of operational monitoring information for environment and security applications. Within the Copernicus program, ESA is responsible for the development of the Space Component and Ground Segment..

The Sentinel-3 (S3) is a Global Land and Ocean Mission [1] currently in development as part of the European Commission’s Copernicus programme (former: Global Monitoring for Environment and Security (GMES) [2]).

The multi-instrument Sentinel-3 mission measures sea-surface topography, sea- and land-surface temperature, ocean colour and land colour to support ocean forecasting systems, as well as environmental and climate monitoring with near-real time data.

The Geostationary Ocean Color Imager II (GOCI-II) is the next generation of GOCI, which is one of the main payloads of the Korean COMS satellite. GOCI was the first ocean color sensor in the world operating on the geostationary orbit.

METimage is a cross-purpose medium resolution, multi-spectral optical imaging instrument dedicated for operational meteorology, oceanography, and climate applications. It is implemented as passive imaging spectro-radiometer, capable of measuring thermal radiance emitted by the Earth and solar backscattered radiation in a broad spectral range.

As part of the Space Situational Awareness Programme (SSA), ESA has initiated the assessment of two missions currently foreseen to be implemented to enable enhanced space weather monitoring. These missions utilize the positioning of satellites at the Lagrangian L1 and L5 points. These Phase 0 or Pre-Phase A mission studies are about to be completed and will thereby have soon passed the Mission Definition Review. Phase A studies are planned to start in 2017. The space weather monitoring system currently considers four remote sensing optical instruments and several in-situ instruments to analyse the Sun and the solar wind conditions, in order to provide early warnings of increased solar activity and to identify and mitigate potential threats to society and ground, airborne and space based infrastructure. The suggested optical instruments take heritage from ESA and NASA science missions like SOHO, STEREO and Solar Orbiter, but the instruments are foreseen to be optimized for operational space weather monitoring purposes with high reliability and robustness demands. The instruments are required to provide high quality measurements particularly during severe space weather events. The program intends to utilize the results of the on-going ESA instrument prototyping and technology development activities, and to initiate pre-developments of the operational space weather instruments to ensure the required maturity before the mission implementation.

Mars is the most similar planet as the Earth in the solar system. So it is the most studied planets in the solar system. U.S.A., Russia and E.U. have launched more than 43 satellites or spacecraft. China has realized to surround and land on the Moon, but has never been to explore Mars.

Gravitational wave (GW), predicted by A. Einstein in his general theory of relativity, is temporal variation of spatial distortion caused from the change of enormous mass such as inspiral and merger of neutron star binaries, black hole binaries, explosion of supernovae, and inflation in early universe.

Nowadays, space-borne differential absorption lidar (DIAL) instruments are under investigation by space agencies to monitor the integrated column density or the atmospheric density profile of gaseous species from space to ground.

ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission and the American-German Gravity Recovery and Climate Experiment (GRACE) mission map the Earth’s gravity field and deliver valuable data for climate research.

The French-German Methane Remote Sensing LIDAR Mission (MERLIN) planned for launch in 2020 aims to provide a global methane concentration map. The instrument is a differential absorption LIDAR (DIAL) system measuring the column-weighted dry-air mixing ratios of methane with a horizontal resolution of 50 km employing an absorption line at 1645 nm [1].

High-energy mid-infrared nanosecond sources are required in a number of applications including biomedicine, remote sensing, and standoff countermeasures, to name just a few. Sources which serve these applications include mid-infrared fiber and solid-state lasers, quantum cascade lasers, as well as optical parametric oscillators (OPO).

Fiber lasers entered numerous applications due to their high efficiency and superior stability. Er-doped fiber lasers emitting around 1550 nm optical wavelength are capable to produce hundreds of Watts [1] and Millijoule pulse energy [2,3].

Semiconductor light sources like light emitting diodes (LEDs) or laser diodes (LDs) are the most important light sources for space applications. LEDs are used in the control panels or lightning systems in the spacecrafts and as growth lightning systems in a deep space.

A new conduction cooled compact laser for SuperCam LIBS-RAMAN instrument aboard Mars 2020 Rover is presented. An oscillator generates 30mJ at 1µm with a good spatial quality. A Second Harmonic Generator (SHG) at the oscillator output generates 15 mJ at 532 nm. A RTP electro-optical switch, between the oscillator and SHG, allows the operation mode selection (LIBS or RAMAN). Qualification model of this laser has been built and characterised. Environmental testing of this model is also reported.

For space-borne atmospheric LIDAR instruments, a manifold of scientific applications exists. But due to the lack of high energy laser sources providing the performance, reliability and lifetime necessary to operate such instruments in space, realization is seen by the community as still very critical.

A high-precision opto-mechanical breadboard for a lens mount has been assembled by means of a laserbased soldering process called Solderjet Bumping; which thanks to its localized and minimized input of thermal energy, is well suited for the joining of optical components made of fragile and brittle materials such as glasses. An optical element made of a silica lens and a titanium barrel has been studied to replicate the lens mounts of the afocal beam expander used in the LIDAR instrument (ATLID) of the ESA EarthCare Mission, whose aim is to monitor molecular and particle-based back-scattering in order to analyze atmosphere composition. Finally, a beam expander optical element breadboard with a silica lens and a titanium barrel was assembled using the Solderjet Bumping technology with Sn96.5Ag3Cu0.5 SAC305 alloy resulting in a low residual stress (<1 MPa) on the joining areas, a low light-depolarization (<0.2 %) and low distortion (wave-front error measurement < 5 nm rms) on the assemblies. The devices also successfully passed humidity, thermal-vacuum, vibration, and shock tests with conditions similar to the ones expected for the ESA EarthCare mission and without altering their optical performances.

Accurate prediction of the arrival of solar wind phenomena, in particular coronal mass ejections (CMEs), at Earth, and possibly elsewhere in the heliosphere, is becoming increasingly important given our ever-increasing reliance on technology. The potentially severe impact on human technological systems of such phenomena is termed space weather. A coronagraph is arguably the instrument that provides the earliest definitive evidence of CME eruption; from a vantage point on or near the Sun-Earth line, a coronagraph can provide near-definitive identification of an Earth-bound CME. Currently, prediction of CME arrival is critically dependent on ageing science coronagraphs whose design and operation were not optimized for space weather services. We describe the early stages of the conceptual design of SCOPE (the Solar Coronagraph for OPErations), optimized to support operational space weather services.

A Japan-led international solar mission “SOLAR-C” is being proposed for mid-2020s launch.

The Microchannel X-ray Telescope (MXT) is a soft X-rays instrument on board SVOM, a Sino French mission. The launch is planned in 2021 by a LM-2C rocket. The main SVOM general objective is the survey of Gamma Ray Bursts, in coordination with ground telescopes. The other main on board instruments are ECLAIR (gamma, french), GRM (gamma, Chinese) and VT (visible, chinese).

The principles of biomimetics have been successfully applied in space optics, e.g. in Lobster-Eye X-ray optical systems. However, the recent increase in knowledge on vision of sea animals, especially on mirror eyes of scallops, crustaceans, and deep sea fishes, makes possible to consider other such applications. Especially the discoveries of mirror eyes of the deep sea fishes Dolichopteryx longipes and Rhynchohyalus natalensis are promising because of their unique arrangements and likely active optics.

The Euclid Near Infrared Spectro-Photometer (NISP) optical system consists of a large filter and GRISM wheel, 4 aspherical lenses with a large diameter of up to 168mm and an Infrared detector array.

The nanosatellite ATISE is a mission dedicated to the observation of the emission spectra of the upper atmosphere (i.e. Airglow and Auroras) mainly related to both the solar UV flux and the precipitation of suprathermal particles coming from the solar wind through the magnetosphere. ATISE will measure specifically the auroral emissions, and the airglow (day- and night) in the spectral range between 380 and 900 nm at altitudes between 100 and 350 km. The exposure time will be 1 second in auroral region and 20 s at low latitude regions. The 5 year expected lifetime of this mission should cover almost a half of solar cycle (2 years nominal). This instrument concept is based on an innovative miniaturized Fourier-transform spectrometer (FTS) allowing simultaneous 1 Rayleigh sensitivity detection along six 1.5°x1° limb lines of sight. This 1-2kg payload instrument is hosted in a 12U cubeSat where 6U are allocated to the payload and 6U to the plateform subsystems. This represents a miniaturisation by a factor of 500 on weight and volume compared to previous Arizona-GLO instrument for equivalent performances in the visible. The instrument is based on microSPOC concept developed by ONERA and IPAG using one Fizeau interferometer per line of sight directly glued on top of the half of a very sensitive CMOS Pyxalis HDPYX detector. Three detectors are necessary with a total electrical consumption compatible with a 6U nanoSat. Each interferometer occupies a 1.4 M pixel part of detector, each is placed on an image of the entrance pupil corresponding to a unique direction of the six lines of sight, this in order to have a uniform illumination permitting good spectral Fourier reconstruction from fringes created between the Fizeau plate and the detector itself. Despite a limited 8x6 cm telescope, this configuration takes advantage of FTS multiplex effect and permits us to maximize the throughput and to integrate very faint emission lines over a wide field of view even if the 1 second integrated signal is comparable to the detector noise.

In Earth Observation, Universe Observation and Planet Exploration, scientific return of the instruments must be optimized in future space missions.

Recently optical sensing solutions based on fiber Bragg grating (FBG) technology have been proposed for temperature monitoring in telecommunication satellite platforms with an operational life time beyond 15 years in geo-stationary orbit. Developing radiation hardened optical interrogators designed to be used with FBG sensors inscribed in radiation tolerant fibers offer the capabilities of multiplexing multiple sensors on the same fiber and reducing the overall weight by removing the copper wiring harnesses associated with electrical sensors.

Here we propose the use of a tunable laser based optical interrogator that uses a semiconductor MG-Y type laser that has no moving parts and sweeps across the C-band wavelength range providing optical power to FBG sensors and optical wavelength references such as athermal Etalons and Gas Cells to guarantee stable operation of the interrogator over its targeted life time in radiation exposed environments. The MG-Y laser was calibrated so it remains in a stable operation mode which ensures that no mode hops occur due to aging of the laser, and/or thermal or radiation effects.

The key optical components including tunable laser, references and FBGs were tested for radiation tolerances by emulating the conditions on a geo-stationary satellite including a Total Ionizing Dose (TID) radiation level of up to 100 krad for interrogator components and 25 Mrad for FBGs.

Different tunable laser control, and signal processing algorithms have been designed and developed to fit within specific available radiation hardened FPGAs to guarantee operation of a single interrogator module providing at least 1 sample per second measurement capability across <20 sensors connected to two separate optical channels.

In order to achieve the required temperature specifications of ±0.5°C across a temperature range of -20°C to +65°C using femtosecond inscribed FBGs (fs-FBG), a polarization switch is used to mitigate for the polarization dependent frequency shift (PDFS) induced from fs-FBG which could be in the order of < 20 pm causing < 2°C error in the measurement. Also special transducers were designed to isolate the strain from the FBGs to reduce any strain influence on the FBG temperature measurements while ensuring high thermal conductivity.

In this paper we demonstrate the operation of an optical FBG interrogator as part of a hybrid sensor bus (HSB) engineering model system developed in the frame of an ESA-ARTES program and is planned to be deployed as a flight demonstrator on-board the German Heinrich Hertz geo-stationary satellite.

Atmospheric reentry transition is produced at hypersonic velocity and is accompanied by a sharp excessive heat load for a few minutes, on the exposed materials, leading to a temperature increase of more than 1000°C. MPBC developed optical fiber sensors for such temperatures with special packaging optimizing between protective capability and fast thermal conductivity. The fiber sensors were calibrated with thermocouples first using standard oven, then with stationary plasma at Von Karman Institute (Belgium) followed by a test within a wind tunnel (1000°C, 8 Mach number) at DLR-Cologne.

One of the promising space applications areas for fibre sensing is high reliable thermal mapping of metrology structures for effects as thermal deformation, focal plane distortion, etc. Subsequently, multi-point temperature sensing capability for payload panels and instrumentation instead of, or in addition to conventional thermo-couple technology will drastically reduce electrical wiring and sensor materials to minimize weight and costs.

Current fiber sensing technologies based on solid state ASPIC (Application Specific Photonic Integrated Circuits) technology, allow significant miniaturization of instrumentation and improved reliability. These imperative aspects make the technology candidate for applications in harsh environments such as space. One of the major aspects in order to mature ASPIC technology for space is assessment on radiation hardness. This paper describes the results of radiation hardness experiments on ASPIC including typical multipoint temperature sensing and thermal mapping capabilities.

In this paper we present the design of smart satellite panels with integrated optical fibers for sensing and data communication. The project starts with a detailed analysis of the system needs and ends with a demonstrator breadboard showing the full performance during and after environmental tests such as vibrations and temperature.

Future science missions will need higher bandwidth in the Gbit/s range for intra-satellite communications, so the step from electrical transmission media towards fiber-optical media is the logical next step to cope with future requirements. In addition, the fibers can be used to monitor temperatures directly underneath satellite payloads which will reduce the integration effort in a later phase. For temperature monitoring so called fiber Bragg gratings (FBGs) are written in special radiation tolerant fibers, which reflection wavelength allows a direct link to temperature at the grating position. A read-out system for FBGs to use within satellite applications is currently under development at OHB.

For this study, first the environmental requirements for the panels are derived and in a second stage the functional requirements are defined. To define the functional requirements a telecommunication satellite platform, in the case here the Small-GEO series from OHB, has been taken as baseline. Based on the configuration of temperature sensors, communication lines and electrical signaling a possible replacement by fiber-optical technology was defined and traded w.r.t. its economic benefit.

It has been pointed out that the replacement of temperature sensors will reduce harness mass, but the great benefit is seen here in the reduction of assembly effort. Once the satellite panel is manufactured, the temperature sensors are already implemented at certain positions. Another point for mass savings which has pointed out is the replacement of the high-voltage or high- current high power commands (HPC) by fiber optics. Replacing some of the several hundred of required HPC lines with very light-weight fibers would reduce the HPC harness by some tens of kilograms. A detailed table illustrating the mass savings and also the integration time savings will be presented in the paper.

To keep the track on an economic solution also a detailed market research was carried out to find suitable components for fiber-optical connectors, fibers and protections buffers. Specially for the connectors a solution based on military qualified connectors pointed out to be the most interesting solution in terms of price and functionality, especially when using multi-pole connectors.

The project closes with the construction of a breadboard demonstrator consisting of three different panels, one large panel (ca. 1 m²) and two smaller panels (ca. 0.3 m²). The large panel and one of the small panels are made out of aluminum facesheets whereas the other small panels is made out of CFRP.

The status of carbon nanotubes (CNT) as outstanding superblack coatings has been established in the recent years, and records in terms of absorbance in the UV-visible-NIR spectral range have been reported.

Light scattering can critically affect the performance of high-end optical systems. For instance, unavoidable but small residual imperfections of optical components such as surface or coating roughness, bulk inhomogeneities, and defects as well as the interaction of light with apertures and baffles give rise to light scattering propagating through the optical system which degrades the imaging quality and leads to a loss of the optical throughput.

Optical instrumentation on space platforms, typically needs to adhere to high quality standards, in particular as far as robustness to the applicable environment is concerned. The term ‘environment’ typically encompasses all types of loads that a system or component might encounter and is required to survive during its lifetime in space without loss of performance.

Stray light is a significant issue in optical design and can dramatically influence the performance of the optical system.

This work describes several OGSEs (Optical Ground Support Equipment) developed by INTA (Spanish Institute of Aerospace Technology – Instituto Nacional de Técnica Aeroespacial) for the calibration and characterization of their self-manufactured multichannel radiometers (Solar Irradiance Sensors - SIS) for planetary atmospheric studies in the frame of some Martian missions at which INTA is participating.

The METimage instrument is designed to serve the VIS/IR Imaging Mission (VII) of the EUMETSAT Polar System – Second Generation.

CHEOPS (CHaracterising ExOPlanet Satellite) is the first ESA Small Mission as part of the ESA Cosmic Vision program 2015-2025 and it is planned launch readiness end of 2017.

The mission lead is performed in a partnership between Switzerland, led by the University of Bern, and the European Space Agency with important contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom.

The CHEOPS mission will be the first space telescope dedicated to search for exoplanetary transits on bright stars already known to host planets by performing ultrahigh precision photometry on bright starts whose mass has been already estimated through spectroscopic surveys on ground based observations.

The number of exoplanets in the mass range 1-30 MEarth for which both mass and radius are known with a good precision is extremely limited also considering the last two decades of high-precision radial velocity measurement campaigns and the highly successful space missions dedicated to exoplanets transit searches (CoRoT and Kepler).

Optical amplifiers have many applications in space, such as transmitters, receivers, for satellite telecom, lidars and remote sensing.

There is increasing interest in the use of optical methods for managing RF signals in space, with applications for both ground-to-satellite and inter-satellite communications readily envisaged. The potential weight-saving of optical fiber over metallic waveguide or coaxial channels is very significant; moreover, there are obvious advantages to be gained from the enormous data capacity of multiplexed fiber links.

Laser communications has been identified as the technology to enable high-data rate, secure links between and within satellites, as well as between satellites and ground stations with decreased mass, size, and electrical power compared to traditional RF technology.

Erbium doped fibers (EDFs) based devices are widely employed in space for optical communication [1], remote sensing [2], and navigation applications, e.g. interferometric fiber optic gyroscope (IFOG). However, the EDF suffers severely radiation induced attenuation (RIA) in radiation environments, e.g. space applications and nuclear reactors [3].

Many different environmental factors can have an effect on optical coating durability for space applications. This includes in-orbit effects such as vacuum exposure, UV radiation, particle radiation, atomic oxygen, thermal cycling, contamination and orbital debris, as well as ground based effects such as cleaning, contamination and humidity [1].

Future investigations of astronomical X-ray sources require light weight telescope systems with large collecting areas and good angular resolution. The Wolter I type telescope design offers a suitable possibility for obtaining performant X-ray mirrors with high collecting areas. The technology based on replicated slumped glass optics using thin glasses thereby provides the opportunity to fulfil the light weight and mass production requirements. In NASA's telescope NuSTAR this technology has been proven as advantageous compared to previous systems. Coating thin glasses with iridium, gold or platinum enhances the reflectivity of X-ray mirrors.

Today, the demand on flat optical components with specification on final surface flatness that must be smaller than ?/20 or ?/30 peak to valley, for various applications including linear accelerators [1,2], space applications [3]…, needs an accurate knowledge on the mechanical stress induced in thin films. In order to design correctly stacks of thin films on both side of a substrate and achieve perfect stress compensation, it is thus obvious that the first step is to precisely characterize the stress in single layers.

Multispectral or hyperspectral images allow acquiring new information that could not be acquired using colored images and, for example, identifying chemical species on an observed scene using specific highly selective thin film filters. Those images are commonly used in numerous fields, e.g. in agriculture or homeland security and are of prime interest for imaging systems for onboard scientific applications (e.g. for planetology).

Optical coatings are widely used in space instrumentation for obtaining antireflection and high-reflection components or for filtering the incoming radiation.

Reosc developed pixelated infrared coatings on detector. Reosc manufactured thick pixelated multilayer stacks on IR-focal plane arrays for bi-spectral imaging systems, demonstrating high filter performance, low crosstalk, and no deterioration of the device sensitivities. More recently, a 5-pixel filter matrix was designed and fabricated. Recent developments in pixelated coatings, shows that high performance infrared filters can be coated directly on detector for multispectral imaging. Next generation space instrument can benefit from this technology to reduce their weight and consumptions.

Sentinel-4 is an imaging UVN (UV-VIS-NIR) spectrometer, developed by Airbus DS under ESA contract in the frame of the joint EU/ESA COPERNICUS program. The mission objective is the operational monitoring of trace gas concentrations for atmospheric chemistry and climate applications – hence the motto of Sentinel-4 “Knowing what we breathe”.

Meteorological satellites have become an irreplaceable weather and ocean observing tool. Since the first Chinese polar-orbiting meteorological satellite was launched successfully in 1988, there are totally 13 meteorological satellites that were launched into both sun synchronous and geostationary orbit.

Many current and future earth observation satellites include spectrometer instruments, due to their suitability for identifying atmospheric gases through spectral signatures. Space based spectrometer instruments, such as the Sentinel-5-UVNS instrument (S5)[1] for the polar-orbiting MetOp Second Generation satellite, require appropriate calibration to incident sunlight in order to provide radiometrically accurate data. To ensure homogenous illumination of the entrance slit of the spectrometer during sunlight calibration, a diffuser is used to scatter the incoming light [1]. One contribution to inaccuracy in sunlight calibration is spectral features, an interference phenomenon resulting from scattering off the calibration unit diffuser [2].

The scattering of the incident light at the diffuser induces path differences, which yield a speckle pattern in the entrance slit. These speckles are still present at the focal plane of modern spectrometers through a combination of the high spectral and spatial resolution [2] [3]. Spectral features originate from the spectral integration of speckles in the slit to the spectrometer detector plane and further integration by the detector pixels [1]. The spectral variation following pixel integration is known as spectral features. The magnitude of this error is evaluated in terms of the Spectral Features Amplitude (SFA), the ratio of the signal standard deviation with its mean value, within a specific wavelength range [4].

This work proposes a novel measurement technique. This method is based on the acquisition of monochromatic speckle patterns in the slit over a finely sampled wavelength range. The net spectral features at the spectrometer detector are evaluated through post processing, by integrating acquired speckle patterns along the spectral resolution, and detector pixels. A key advantage of the proposed technique is the fine sampling and observation of the interference structures that make up spectral features, below the level of a spectrometer pixel. The simplified optical system and simulation of an idealised spectrometer reduces the error contributions when compared to measurement using an entire spectrometer.

The goal of this investigation is the measurement of the S5 spectral features amplitude associated with the Heraeus Optical Diffuser (HOD), a volume diffuser, and the TNO quasi volume diffuser (QVD), in conjunction with qualitative insight into the mechanism behind speckle induced spectral features, supporting the design of future spectrometers.

This paper is structured as follows: Section II details the system designed to acquire monochromatic speckle patterns. The monochromatic speckle patterns are obtained using a tuneable laser capable of wavelength steps below the speckle decorrelation wavelength, as investigated in III. Section IV outlines how monochromatic speckles are integrated to spectral features, and reports the SFA values for the HOD and QVD. The spectral features results are discussed in light of this inference in Section V, with conclusions presented in Section VI.

Presentation titled, "AOTF spectrometers in space missions and their imaging capabilities"

In recent years TNO has investigated and developed different innovative opto-mechanical designs to realize advanced spectrometers for space applications in a more compact and cost-effective manner. This offers multiple advantages: a compact instrument can be flown on a much smaller platform or as add-on on a larger platform; a low-cost instrument opens up the possibility to fly multiple instruments in a satellite constellation, improving both global coverage and temporal sampling (e.g. multiple overpasses per day to study diurnal processes); in this way a constellation of low-cost instruments may provide added value to the larger scientific and operational satellite missions (e.g. the Copernicus Sentinel missions); a small, lightweight spectrometer can easily be mounted on a small aircraft or high-altitude UAV (offering high spatial resolution).

SPEX is developed as part of the roadmap for optical instruments of the Netherlands Space Office to support environment and climate research [1].

The COP21 climate conference has taken place in December 2015 in Paris, France.

After the successful closure of the Critical Design Review (CDR), the development of the ESA (European Space Agency) ATmospheric LIDAR (Light Detection and Ranging) is now approaching the completion of the manufacturing and testing of all its units and the start of the full instrument integration and qualification campaign.

The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO₂) measurements due to the existence of distinct absorption features for the gas at this wavelength region [1]. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers [2]. Currently, LaRC team is engaged in designing, developing and demonstrating a triple-pulsed 2-micron direct detection Integrated Path Differential Absorption (IPDA) lidar to measure the weighted-average column dry-air mixing ratios of carbon dioxide (XCO₂) and water vapor (XH₂O) from an airborne platform [1, 3-5]. This novel technique allows measurement of the two most dominant greenhouse gases, simultaneously and independently, using a single instrument. This paper will provide status and details of the development of this airborne 2-micron triple-pulse IPDA lidar. The presented work will focus on the advancement of critical IPDA lidar components. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plans for IPDA lidar ground integration, testing and flight validation will also be discussed. This work enables new Earth observation measurements, while reducing risk, cost, size, volume, mass and development time of required instruments.

The Methane Remote Sensing LIDAR Mission (MERLIN) is a joint French-German cooperation on the development, launch and operation of a climate monitoring satellite, executed by the French Space Agency CNES and the German Space Administration DLR.

During the Aeolus laser and instrument transmitter development it was shown that atmosphere quality was one major limiting factor for high energy UV laser operation at ambient pressure. As already proven in literature operation can only be safely obtained in the presence of oxygen ([1] to [6]).

Several possible future spatial lidar missions (MERLIN EXCALIBUR ASCENDS) are intended to measure major greenhouse gases (CO2, H2O, CH4) in order to better understand their cycle and their impact on climate change.

Light detection and ranging (lidar) using lasers is an attractive technique to remotely detect a variety of atmospheric parameters from space.

The generation of satellite communications with flexible and efficient transmission of radio signals requires a large number of low interfering beams and a maximum exploitation of the available frequency spectrum.

In the last decade, Thales Alenia Space has put significant research effort in photonic technologies for satellite applications, with the objective to provide telecom payload systems with enhanced functionality, higher performance and lower costs.

RF frequency down-conversion is of key importance in communication satellites. While the available high-end microwave electronic mixers and circuitry are bulky, heavy, expensive and sensitive to electromagnetic interference (EMI), microwave photonics emerges to be a promising and low-cost alternative.

The evolution of broadband communication satellites shows a clear trend towards an efficient use of the satellite and spectral resources.

Over the past few years considerable attention has been focussed on the inclusion of flexibility in communication satellite payloads. The purpose of this flexibility is to enable a given satellite on command to support different frequency plans, re-configure coverage in response to changing traffic demands and re-configure interconnectivity between coverages.

Data transmission requirements between avionics modules onboard spacecraft continue to increase, driven by the use of processors with high-speed serial data I/O to support the growing data requirements of advanced sensor systems and increased bandwidth of communications switches and satellite communications terminals.

The JWST is an international collaboration among the NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). It is a large (6.5 m primary mirror diameter), infrared (0.6-27 ?m) observatory that will study the first galaxies of the early Universe, the birth of stars and protoplanetary systems as well as exoplanets.

The Environmental Mapping and Analysis Program (EnMAP) is a German hyperspectral satellite mission that aims at monitoring and characterizing the Earth’s environment.

The current generation of terrestrial telescopes has large enough primary mirror diameters that active optical control based on wavefront sensing is necessary. Similarly, in space, while the Hubble Space Telescope (HST) has a mostly passive optical design, apart from focus control, its successor the James Webb Space Telescope (JWST) has active control of many degrees of freedom in its primary and secondary mirrors.

The Environmental Mapping and Analysis Program (EnMAP) is a German hyperspectral mission with pushbroom type imaging spectrometers covering the wavelength ranges from 420 nm to 2450 nm. The ground sampling distance is 30 m with a total swath of 30 km, while the spectral sampling distance is roughly 5 nm to 12 nm.

Deployable optics have the potential of revolutionizing the field of high resolution Earth Observation. By offering the same resolutions as a conventional telescope, while using a much smaller launch volume and mass, the costs of high resolution image data can be brought down drastically. In addition, the technology will ultimately enable resolutions that are currently unattainable due to limitations imposed by the size of launcher fairings.

To explore the possibilities and system complexities of a deployable telescope, a concept study was done to design a competitive deployable imager. A deployable telescope was designed for a ground sampling distance of 25 cm from an orbital altitude of 550 km. It offers an angular field of view of 0.6° and has a panchromatic channel as well as four multispectral bands in the visible and near infrared spectrum.

The optical design of the telescope is based on an off-axis Korsch Three Mirror Anastigmat. A freeform tertiary mirror is used to ensure a diffraction limited image quality for all channels, while maintaining a compact design. The segmented primary mirror consists of four tapered aperture segments, which can be folded down during launch, while the secondary mirror is mounted on a deployable boom. In its stowed configuration, the telescope fits within a quarter of the volume of a conventional telescope reaching the same resolution.

To reach a diffraction limited performance while operating in orbit, the relative position of each individual mirror segment must be controlled to a fraction of a wavelength. Reaching such tolerances with deployable telescope challenging, due to inherent uncertainties in the deployment mechanisms. Adding to the complexity is the fact that the telescope will be operating in a Low Earth Orbit (LEO) where it will be exposed to very dynamic thermal conditions. Therefore, the telescope will be equipped with a robust calibration system. Actuators underneath the primary mirror will be controlled using a closed-loop system based on measurements of the image sharpness as well as measurements obtained with edge sensors placed between the mirror segments. In addition, a phase diversity system will be used to recover residual wavefront aberrations.

To aid the design of the deployable telescope, an end-to-end performance model was developed. The model is built around a dedicated ray-trace program written in Matlab. This program was built from the ground up for the purpose of modelling segmented telescope systems and allows for surface data computed with Finite Element Models (FEM) to be imported in the model. The program also contains modules which can simulate the closed-loop calibration of the telescope and it can use simulated images as an input for phase diversity and image processing algorithms. For a given thermo-mechanical state, the end-to-end model can predict the image quality that will be obtained after the calibration has been completed and the image has been processed. As such, the model is a powerful systems engineering tool, which can be used to optimize the in-orbit performance of a segmented, deployable telescope.

High resolution satellite imagery is essential in a wide variety of applications such as urban monitoring, environmental protection, disaster response, precision farming, defence and security.

As the number of smallsats and cubesats continues to increase [1], so does the interest in the space optics community to miniaturize reflective optical instrumentation for these smaller platforms. Applications of smallsats are typically for the Earth observing community, but recently opportunities for them are being made available for planetary science, heliophysics and astrophysics concepts [2]. With the smaller satellite platforms come reduced instrument sizes that they accommodate, but the specifications such as field of view and working f/# imposed on the smaller optical systems are often the same, or even more challenging. To meet them, and to “fit in the box”, it is necessary to employ additional degrees of freedom to the optical design. An effective strategy to reduce package size is to remove rotational symmetry constraints on the system layout, allowing it to minimize the unused volume by applying rigid body tilts and decenters to mirrors. Requirements for faster systems and wider fields of view can be addressed by allowing optical surfaces to become “freeform” in shape, essentially removing rotational symmetry constraints on the mirrors themselves. This dual approach not only can reduce package size, but also can allow for increased fields of view with improved image quality. Tools were developed in the 1990s to compute low-order coefficients of the imaging properties of asymmetric tilted and decentered systems [3][4]. That approach was then applied to reflective systems with plane symmetry, where the coefficients were used to create closed-form constraints to reduce the number of degrees of freedom of the design space confronting the designer [5][6]. In this paper we describe the geometric interpretation of these coefficients for systems with a plane of symmetry, and discuss some insights that follow for the design of systems without closed-form constraints. We use a common three-mirror design form example to help illustrate these concepts, and incorporate freeform surfaces for each mirror shape. In section II, we evoke the typical form of the wave aberration function taught in most texts on geometrical optics, and then recast it into a general form that no longer assumes rotational symmetry. A freeform surface definition for mirrors is then defined, and the example three-mirror system used throughout this paper is introduced. In section III, the first-order coefficients of the plane symmetric system are discussed, and then the second-order in section IV. In both of these discussions, the example system is perturbed to present the explicit form of the aberration coefficient laid out in section II, and plots are presented using optical design software. Finally, some concluding remarks are given in section V.

The space mission Arago is proposed as a candidate to ESA’s Cosmic Vision M5 call by the UVMag consortium. Arago is dedicated to the study of the dynamic 3D environment of stars and planets. Thanks to a high-resolution UV and visible spectropolarimeter, the instrument will detect and characterize the magnetic fields of the stars, their environment and its impact on exoplanets. Scientific requirements impose a wide spectral range from 119 to 888 nm with a single full-Stokes polarimeter followed by two high-resolution spectrographs. To achieve these stringent specifications, a polychromatic concept of polarimeter has been studied and tested thanks to a R and T study funded by CNES. Using an optimized combination of Magnesium Fluoride plates followed by a polarization analyzer, it measures all four Stokes parameters with a constant efficiency over the spectral range. This is performed with a sequence of 6 sub-exposures acquired with different plate angles. The two orthogonal polarized beams coming out of the polarimeter feed two spectrographs. The UV spectrograph has a spectral resolution of at least 25000 over its spectral range, while the visible spectrograph works at least at 35000. Finally, to image the high-resolution spectra, a CCD detector and a MCP were chosen for the visible and UV arms of the instrument respectively.

This paper describes the complete optical design of Arago’s instrument, as proposed to ESA as an answer to its M5 call, from the 1.3-m diameter telescope to the detectors. The design of the polarimeter is presented as well as the unusual way of demodulating the polarization information, in order to have a polychromatic polarimeter working with the same efficiency from FUV to NIR. The optical design of the UV and visible échelle spectrographs and their detection chains are also presented, as well as the achieved performances.

Straylight is a spurious effect that can seriously degrade the radiometric accuracy achieved by Earth observing optical instruments, as a result of the high contrast in the observed Earth radiance scenes and spectra. It is considered critical for several ESA missions such as Sentinel-5, FLEX and potential successors to CarbonSat. Although it is traditionally evaluated by Monte-Carlo simulations performed with commercial softwares (e.g. ASAP, Zemax, LightTools), semi-analytical approximate methods [1,2] have drawn some interest in recent years due to their faster computing time and the greater insight they provide in straylight mechanisms. They cannot replace numerical simulations, but may be more advantageous in contexts where many iterations are needed, for instance during the early phases of an instrument design.

CarbonSat was a candidate satellite mission in the frame of ESA’s Living Planet Programme, which targeted high-precision measurements of carbon dioxide (CO2) and methane (CH4) concentrations from space.

We introduce to astrophysical instrumentation and space optics the use of Virtually Imaged Phased Array (VIPA) to shrink échelle spectrographs and/or increase their resolution.

The FLEX mission is the 8th Earth Explorer mission selected for flight. It will quantify photosynthetic activity and plant stress by mapping vegetation fluorescence. It will advance our understanding of the functioning of the photosynthetic mechanisms and the actual health and performance of terrestrial vegetation.

Sentinel 4 is an imaging UVN (UV-VIS-NIR) dispersive spectrometer, developed by Airbus DS under an ESA contract in the frame of the joint EU/ESA COPERNICUS program. The instrument is introduced in a dedicated presentation in this conference.

Many planetary surface processes leave evidence as small features in the sub-millimetre scale. Current planetary X-ray fluorescence spectrometers lack the spatial resolution to analyze such small features as they only provide global analyses of areas <100 mm2. A micro-XRF spectrometer will be deployed on the NASA Mars 2020 rover to analyze spots as small as 120μm.

FLEX (Fluorescence Explorer) has been recently approved by the Earth Observation Programme Board as the next Earth Explorer 8 mission.

The Environmental Mapping and Analysis Program (EnMAP) is a German space borne science mission that aims at characterizing the Earth’s environment on a global scale. The single payload of the satellite is the hyper spectral imager (HSI). It is capable of measuring the solar radiance reflected from the Earth’s surface as a continuous spectrum in the spectral range of 420nm to 2450nm, with a spectral sampling of 6.5nm (VNIR) and 10nm (SWIR). The EnMAP swath of 30km is sampled in spatial direction with 30m.

On July 2020, NASA will launch the Mars2020 mission. This mission consists in landing an instrumented rover on the Martian surface in order to characterize the geology and history of a new landing site on Mars, investigate Mars habitability, seek potential biosignatures, cache samples for an eventual return to Earth, and demonstrate in-situ production of oxygen needed for human exploration.

NASA is developing the MARS 2020 mission, which includes a rover that will land and operate on the surface of Mars. MARS 2020, scheduled for launch in July, 2020, is designed to conduct an assessment of Mars’ past habitability, search for potential biosignatures, demonstrate progress toward the future return of samples to Earth, and contribute to NASA’s Human Exploration and Space Technology Programs.

A new multi-spectral line scanner CMOS image sensor is reported. The backside illuminated (BSI) image sensor was designed for continuous scanning Low Earth Orbit (LEO) space applications including A custom high quality CMOS Active Pixels, Time Delayed Integration (TDI) mechanism that increases the SNR, 2-phase exposure mechanism that increases the dynamic Modulation Transfer Function (MTF), very low power internal Analog to Digital Converters (ADC) with resolution of 12 bit per pixel and on chip controller. The sensor has 4 independent arrays of pixels where each array is arranged in 2600 TDI columns with controllable TDI depth from 8 up to 64 TDI levels. A multispectral optical filter with specific spectral response per array is assembled at the package level. In this paper we briefly describe the sensor design and present some electrical and electro-optical recent measurements of the first prototypes including high Quantum Efficiency (QE), high MTF, wide range selectable Full Well Capacity (FWC), excellent linearity of approximately 1.3% in a signal range of 5-85% and approximately 1.75% in a signal range of 2-95% out of the signal span, readout noise of approximately 95 electrons with 64 TDI levels, negligible dark current and power consumption of less than 1.5W total for 4 bands sensor at all operation conditions .

The Stereo Camera (STC), mounted on-board the BepiColombo spacecraft, will acquire in push frame stereo mode the entire surface of Mercury. STC will provide the images for the global three-dimensional reconstruction of the surface of the innermost planet of the Solar System. The launch of BepiColombo is foreseen in 2018. STC has an innovative optical system configuration, which allows good optical performances with a mass and volume reduction of a factor two with respect to classical stereo camera approach. In such a telescope, two different optical paths inclined of ±20°, with respect to the nadir direction, are merged together in a unique off axis path and focused on a single detector. The focal plane is equipped with a 2k x 2k hybrid Si-PIN detector, based on CMOS technology, combining low read-out noise, high radiation hardness, compactness, lack of parasitic light, capability of snapshot image acquisition and short exposure times (less than 1 ms) and small pixel size (10 μm).

During the preflight calibration campaign of STC, some detector spurious effects have been noticed. Analyzing the images taken during the calibration phase, two different signals affecting the background level have been measured. These signals can reduce the detector dynamics down to a factor of 1/4th and they are not due to dark current, stray light or similar effects.

In this work we will describe all the features of these unwilled effects, and the calibration procedures we developed to analyze them.

Recent European atmospheric imaging missions have seen a move towards the use of CMOS sensors for the visible and NIR parts of the spectrum. These applications have particular challenges that are completely different to those that have driven the development of commercial sensors for applications such as cell-phone or SLR cameras. This paper will cover the design and performance of general-purpose image sensors that are to be used in the MTG (Meteosat Third Generation) and MetImage satellites and the technology challenges that they have presented. We will discuss how CMOS imagers have been designed with 4T pixel sizes of up to 250 μm square achieving good charge transfer efficiency, or low lag, with signal levels up to 2M electrons and with high line rates. In both devices a low noise analogue read-out chain is used with correlated double sampling to suppress the readout noise and give a maximum dynamic range that is significantly larger than in standard commercial devices. Radiation hardness is a particular challenge for CMOS detectors and both of these sensors have been designed to be fully radiation hard with high latch-up and single-event-upset tolerances, which is now silicon proven on MTG. We will also cover the impact of ionising radiation on these devices. Because with such large pixels the photodiodes have a large open area, front illumination technology is sufficient to meet the detection efficiency requirements but with thicker than standard epitaxial silicon to give improved IR response (note that this makes latch up protection even more important). However with narrow band illumination reflections from the front and back of the dielectric stack on the top of the sensor produce Fabry-Perot étalon effects, which have been minimised with process modifications. We will also cover the addition of precision narrow band filters inside the MTG package to provide a complete imaging subsystem. Control of reflected light is also critical in obtaining the required optical performance and this has driven the development of a black coating layer that can be applied between the active silicon regions.

Europe has currently no full supply chain of CMOS image sensors (CIS) for space use, certainly not in terms of image sensor manufacturing. Although a few commercial foundries in Europe manufacture CMOS image sensors for consumer and automotive applications, they are typically not interested in adapting their process flow to meet high-end performance specifications, mainly because the expected manufacturing volume for space imagers is extremely low.

This paper reports on a Time Delay and Integration image sensor System-on-Chip realized in an embedded CCD process. The integration of single-poly CCD modules into a standard 0.13?m CMOS process is discussed. The technology performance has been evaluated using dedicated test structures. Next, a prototype TDI imager with 5?m pixel pitch, 512 rows and 1024 columns was designed, manufactured and characterized. Charge Transfer Efficiency greater than 0.9999 up till very high line rates of 400kHz was recorded.

In recent years, the demand for high-capacity communication has grown, and fiber-optic transmission is being used in wired communications to meet this demand. Similarly, free-space optics (FSO), which is an optical wireless communication technology that uses laser light, has attracted much attention and has been considered as a suitable alternative to satisfy this demand in wireless communications. Free-space optical communication uses a hundred THz frequency band and allows for high-speed and radio-regulation free transmission, which may provide a solution for the current shortage of radio frequency bands.

In this paper, the potential of hybrid automatic-repeat request (HARQ) algorithm in enhancing the performance of a free- space optical (FSO) communication system, which is impaired by weak turbulence and non-negligible residual pointing error, is explored. In particular, the FSO system is assumed to use orthogonal Hermite-Gaussian (HG) beam patterns to exploit spatial multiplexing of optical radiation. Furthermore, it is assumed that a direct-detection mechanism is utilized at the receiver and that the optical radiation is modulated using pulse-position modulation (PPM). Via analytical results and numerical analysis, it is demonstrated that HARQ not only overcomes the impact of spatial error, but also offers a means of achieving near error free communications provided that the delay associate with HARQ can be tolerated. In general, HARQ offers several orders of magnitude improvement in performance.

EDRS-C will operate on a geostationary orbit as the second node of the European Data Relay System (EDRS). The EDRS-C satellite, designed by OHB System as prime contractor, has been procured in the frame of a Public Private Partnership (PPP) between Airbus Defence and Space and ESA. EDRS-C is currently under assembly at OHB facilities in Bremen.

In October 2022 the binary asteroid system 65803 Didymos will have an exceptionally close approach with the Earth flying by within only 0.088 AU. ESA is planning to leverage on this close encounter to launch a small mission of opportunity called Asteroid Impact Mission (AIM) to explore and demonstrate new technologies for future science and exploration missions while addressing planetary defence and performing asteroid scientific investigations.

The OPTEL-μ terminal is designed to transmit data generated on-board LEO satellites to an optical ground station at a data rate of 2 Gbps. This would allow operators of LEO satellites to downlink the large amounts of data being generated by their payload to ground. To make this technology attractive to LEO satellite user community the design of the OPTEL-μ has minimal impact to the spacecraft resources.

Since the successful demonstration of the Semiconductor-laser Inter-satellite Link EXperiment (SILEX) in 2001 between ARTEMIS and SPOT-4 satellites, the European Space Agency (ESA) and several European National Space Agencies have consolidated the effort in developing the so-called “second generation” of optical communications terminals with reduced mass, size and power consumption, and increased data transmission rate, [1].

The Asteroid Impact Mission (AIM) is part of the joint Asteroid Impact and Deflection Assessment (AIDA) project of ESA, DLR, Observatoire de la Côte d´Azur, NASA, and Johns Hopkins University Applied Physics Laboratory (JHU/APL).

National Institute of Information and Communications Technology (NICT) has a long history of the R&D of space laser communications.

High resolution observation systems need bigger and bigger telescopes. The design of such telescopes is a key element for the satellite design. In order to improve the imaging resolution with minimum impact on the satellite, a big effort must be made to improve the compactness of the telescope. Compactness is also important for the agility of the satellite and for the size and cost of the launcher.

The next generation of space telescopes for direct imaging and spectroscopy of exoplanets includes telescopes with a monolithic mirror, such as the Wide Field Infrared Survey Telescope (WFIRST) [1] and Large Ultra-Violet Optical Infrared (LUVOIR) telescopes with segmented primary mirror, like ATLAST [2, 3] or HDST [4].

To increase the collecting power and to improve the angular imaging resolution, space telescopes are evolving towards larger primary mirrors. The aerial density of the telescope mirrors needs to be kept low, however, to be compatible with the launch requirements. A light-weight (primary) mirror will introduce additional optical aberrations to the system. These may be caused by for instance manufacturing errors, gravity release and thermo-elastic effects. Active Optics (AO) is a key candidate technology to correct for the resultant wave front aberrations [1].

Since 20 years, the bimorph deformable mirrors developed by CILAS and their most recent generation called “monomorph” demonstrated their powerful ability to correct the optical aberrations and optimize the performances of numerous ground-based facilities from astronomical telescopes to high-power laser chains.

An active support for large reflective optics is suitable to compensate for manufacturing-induced deformations and (re-)positioning-induced deformations such as induced by slewing of earth-based telescopes.

Large UVOIR (ultraviolet-optical-infrared) space telescopes that are going to be designed within the next decades are intended to answer the question about life on exoplanets [1], [2].

The design of large segmented mirrors, actively controlled both in shape and in differential piston, is one of the challenges space optics is facing, driven by the needs of the astronomical community.

While ambitious plans are being developed for giant, segmented telescopes in space, we feel that a large monolithic mirror telescope would have several advantages in the near term. In particular, the risk involved in deploying the optics will be significantly reduced, and the telescope can provide excellent image quality without the need for precise segment alignment and phasing.

The ICON mission is led by the University of California-Berkeley (Space Sciences Laboratory). In the frame of this mission the Space Center of Liege was involved in the optical design optimization and related analysis, and VUV on ground calibration.

In 2017 the new hyperspectral DLR Earth Sensing Imaging Spectrometer (DESIS) will be integrated in the Multi-User-System for Earth Sensing (MUSES) platform [1] installed on the International Space Station (ISS).

EUCLID mission [1] has been selected by ESA in 2012 in the context of the Cosmic Vision program to understand the nature of the dark energy and the dark matter. It is designed to map the geometry of the dark Universe by investigating the distance-redshift relationship and the evolution of cosmic structures.

Sentinel-5 is part of the Metop SG instrument suite. Metop SG is a series of three Meteorological Operational (MetOp) satellites which will provide continuity and enhancement of these observations in the timeframe of 2020 to 2040.

The Meteosat Third Generation (MTG) Programme will ensure the future continuity and enhancement of meteorological data from geostationary orbit as currently provided by the Meteosat Second Generation (MSG) system. The industrial prime contractor for the space segment is Thales Alenia Space (France), with a core team consortium including OHB System AG (Germany).

The TROPospheric Monitoring Instrument (TROPOMI) is a sun-backscatter imaging spectrometer. It is the single instrument on board ESA’s Copernicus Sentinel-5P satellite, which is now planned for launched in early 2017.

The CCD remains the preeminent visible and ultra-violet wavelength image sensor in space-science, Earth and planetary remote sensing. However, the design of space-qualified CCD readout electronics is a significant challenge with requirements for low-volume, low-mass, low-power, high-reliability and sufficient tolerance to the effects of space radiation.

The intrapixel response is the signal detected by a single pixel illuminated by a Dirac distribution as a function of the position of this Dirac inside this pixel. It is also known as the pixel response function (PRF). This function measures the sensitivity variation at the subpixel scale and gives a spatial map of the sensitivity across a pixel.

3D PLUS has developed in the framework of R and D activities an advanced CMOS camera for Space applications. The Centre National d’Etudes Spatiales (CNES), also called French space agency, is leading the developement of this camera, see Figure 1. This instrument has been integrated using the 3D PLUS technology in order to be as compact as possible. Particular attention has been paid to ensure a good radiation tolerance to cover a wide range of scientific applications such as planetology, but also platform or launcher monitoring and star trackers.

HgCdTe APDs have opened a new horizon in photon starved applications due to their exceptional performance in terms of high linear gain, low excess noise and high quantum efficiency. Both focal plane arrays (FPAs) and large array single element using HgCdTe (MCT) APDs have been developed at CEA/Leti and Sofradir and high performance devices are at present available to detect without deterioration the spatial and/or temporal information in photon fluxes with a low number of photon in each spatio-temporal bin. The enhancement in performance that can be achieved with MCT has subsequently been demonstrated in a wide scope of applications such as astronomical observations, active imaging, deep space telecommunications, atmospheric LIDAR and mid-IR (MIR) time resolved photoluminescence measurements. Most of these applications can be used in space borne platforms.

Lens R&D is currently working on an Artes 5-2 contract aimed at developing an ITAR free extended temperature sunsensor. This sensor should be able to survive the temperature excursions associated with mounting on an extendable solar panel of geostationary satellites.

CHEOPS is an ESA Class S Mission aiming at the characterization of exoplanets through the precise measurement of their radius, using the transit method [1]. To achieve this goal, the payload is designed to be a high precision “absolute” photometer, looking at one star at a time. It will be able to cover la large fraction of the sky by repointing. Its launch is expected at the end of 2017 [2, this conference]. CHEOPS’ main science is the measure of the transit of exoplanets of radius ranging from 1 to 6 Earth radii orbiting bright stars. The required photometric stability to reach this goal is of 20 ppm in 6 hours for a 9th magnitude star. The CHEOPS’ only instrument is a Ritchey-Chretien style telescope with 300 mm effective aperture diameter, which provides a defocussed image of the target star on a single frame-transfer backside illuminated CCD detector cooled to -40°C and stabilized within ~10 mK [2]. CHEOPS being in a LEO, it is equipped with a high performance baffle. The spacecraft platform provides a pointing stability of < 2 arcsec rms. This relatively modest pointing performance makes high quality flat-fielding necessary In the rest of this article we will refer to the only CHEOPS instrument simply as “CHEOP” Its behavior will be calibrated thoroughly on the ground and only a small subset of the calibrations can be redone in flight. The main focuses of the calibrations are the photonic gain stability and sensibility to the environment variations and the Flat field that has to be known at a precision better than 0.1%.

A typical issue of modern space missions is the measurement of the relative attitude (orientation and position in space) of one part of the satellite with respect to the reference frame (main body) of the satellite or the relative attitude of two parts of the same satellite or even two or more satellites flying in formation.

Optical communication between optical ground stations (OGS) and geostationary (GEO) satellites is a promising technology for future high-speed data transfer between Earth and space. However, such optical communication links suffer from distortions caused by atmospheric turbulence. To explore adaptive optics mitigation of this effect both in the uplink and the downlink beam, we have developed an adaptive optics testbed. In an earlier publication [1], we reported on the results of uplink compensation. In this contribution, we wish to elaborate more on the efficiency of downlink compensation. Further, we will highlight the differences between uplink and downlink compensation.

Optical communication in space is already in its operational phase.

Over the past years we have successfully applied adaptive optics (AO) in some optical ground stations (OGS) to improve the signal-to-noise ratio of satellite to ground laser communications.

Communications systems builders continue to search for signal formats and receiver architectures that can provide the most efficient utilization of their subsystems, which include power amplifiers as well as transmit and receive apertures. Receivers requiring very small amounts of received power are of particular interest in communications links where transmission distances are very long and losses are large, such as from Deep Space. Helstrom and others ([1],[2],[3]) initiated the study of optimum signal reception using quantum mechanical signal models. They derived the mathematical description and predicted performance of receivers that optimize certain criteria, such as Minimum Probability of Error (MPE). Unfortunately, practical implementation of their proposed receivers has still not been achieved. In parallel, technology has advanced to where noiseless photon counters can be used to achieve quite good performance ([4]). We show here that, when an end-to-end error correction code is added, in fact such a system can out-perform the “optimum” MPE system at low signal powers. In this report, we derive the formulation of a quantum receiver that is shown to be uniformly better than either the MPE or photon-counting receiver.

Quantum key distribution (QKD), the first applicable quantum technology, is able to distribute a secret key to two parties. This key can then be used as a one-time-pad for absolutely secure communication. The first QKD protocol was the polarization based BB84 protocol proposed in [1]. Since then many QKD protocols have been proposed and investigated [2, 3].

Quantum optics [1] can be harnessed to implement cryptographic protocols that are verifiably immune against any conceivable attack [2]. Even quantum computers, that will break most current public keys [3, 4], cannot harm quantum encryption. Based on these intriguing quantum features, metropolitan quantum networks have been implemented around the world [5-15]. However, the long-haul link between metropolitan networks is currently missing [16]. Existing fiber infrastructure is not suitable for this purpose since classical telecom repeaters cannot relay quantum states [2]. Therefore, optical satellite-to-ground communication [17-22] lends itself to bridge intercontinental distances for quantum communication [23-40].