This paper presents the recent achievements in the development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), a solar coronagraph that is the primary payload of ESA’s formation flying in-orbit demonstration mission PROBA-3. The PROBA-3 Coronagraph System is designed as a classical externally occulted Lyot coronagraph but it takes advantage of the opportunity to place the 1.4 meter wide external occulter on a companion spacecraft, about 150m apart, to perform high resolution imaging of the inner corona of the Sun as close as ~1.1 solar radii. Besides providing scientific data, ASPIICS is also equipped with sensors for providing relevant navigation data to the Formation Flying GNC system. This paper is reviewing the recent development status of the ASPIICS instrument as it passed CDR, following detailed design of all the sub-systems and testing of STM and various Breadboard models.
Three mirror anastigmat (TMA) telescope designs  had been implemented in different projects ranging from the narrow Field-Of-View large instruments as Quickbird (2° FOV)  to smaller telescopes as JSS 12° FOV developed for RapidEye mission .<p> </p>This telescope configuration had been also selected for the PROBA-V payload, the successor of Vegetation, a multispectral imager flown on Spot-4 and subsequently on Spot-5 French satellites for Earth Observation and defence. PROBA-V, small PROBA-type satellite, will continue acquisition of vegetation data after the lifetime of Spot-5 expires in 2012.<p> </p>The PROBA-V TMA optical design achieves a 34° FOV across track and makes use of highly aspherical mirrors. Such a telescope had become feasible due to the recently developed Single Point Diamond Turning fabrication technology. The telescope mirrors and structure are fabricated in aluminium and form an athermal optical system.<p> </p>This paper presents the development of the compact wide FOV TMA, its implementation in PROBA-V multispectral imager and reviews optics fabrication technology that made this development possible. Furthermore, this TMA is being used in combination with a linear variable filter in a breadboard of a compact hyperspectral imager. Moreover, current technology allows miniaturization of TMA, so it is possible to use a TMA-based hyperspectral imager on a cubesat platform.
This paper presents the current status of ASPIICS, a solar coronagraph that is the primary payload of ESA’s formation
flying in-orbit demonstration mission PROBA-3.
The “sonic region” of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity
sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead
to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like
conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of
the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light
corona where the main coronal mass is concentrated.
The PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging
Investigation of the Corona of the Sun) is designed as a classical externally occulted Lyot coronagraph but it takes
advantage of the opportunity to place the external occulter on a companion spacecraft, about 150m apart, to perform high
resolution imaging of the inner corona of the Sun as close as ~1.1 solar radii. The images will be tiled and compressed on
board in an FPGA before being down-linked to ground for scientific analyses.
ASPIICS is built by a large European consortium including about 20 partners from 7 countries under the auspices of the
European Space Agency. This paper is reviewing the recent development status of the ASPIICS instrument as it is
The “sonic region” of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light corona where the main coronal mass is concentrated. The proposed PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), with its novel design, will be the first space coronagraph to cover the range of radial distances between ~1.08 and 3 solar radii where the magnetic field plays a crucial role in the coronal dynamics, thus providing continuous observational conditions very close to those during a total solar eclipse. PROBA-3 is first a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future European missions, which will fly ASPIICS as primary payload. The instrument is distributed over two satellites flying in formation (approx. 150m apart) to form a giant coronagraph capable of producing a nearly perfect eclipse allowing observing the sun corona closer to the rim than ever before. The coronagraph instrument is developed by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency. This paper is reviewing the recent improvements and design updates of the ASPIICS instrument as it is stepping into the detailed design phase.
PROBA-3 is a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future ESA missions. PROBA-3 will fly ASPIICS (Association de Satellites pour l’Imagerie et l’Interferométrie de la Couronne Solaire) as primary payload, which makes use of the formation flying technique to form a giant coronagraph capable of producing a nearly perfect eclipse allowing to observe the sun corona closer to the rim than ever before. The coronagraph is distributed over two satellites flying in formation (approx. 150m apart). The so called Coronagraph Satellite carries the camera and the so called Occulter Satellite carries the sun occulter disc. This paper is reviewing the design and evolution of the ASPIICS instrument as at the beginning of Phase C/D.
Recently, a joint Swiss/Belgian initiative started a project to build a new generation airborne imaging spectrometer, namely APEX (Airborne Prism Experiment) under the ESA funding scheme named PRODEX. APEX is a dispersive pushbroom imaging spectrometer operating in the spectral range between 380 - 2500 nm. The spectral resolution will be better then 10 nm in the SWIR and < 5 nm in the VNIR range of the solar reflected range of the spectrum. The total FOV will be ± 14 deg, recording 1000 pixels across track with max. 300 spectral bands simultaneously. APEX is subdivided into an industrial team responsible for the optical instrument, the calibration homebase, and the detectors, and a science and operational team, responsible for the processing and archiving of the imaging spectrometer data, as well as for its operation. APEX is in its design phase and the instrument will be operationally available to the user community in the year 2006.
Over the past few years, a joint Swiss/Belgium ESA initiative resulted in a project to build a precursor mission of future spaceborne imaging spectrometers, namely APEX (Airborne Prism Experiment). APEX is designed to be an airborne dispersive pushbroom imaging spectrometer operating in the solar reflected wavelength range between 4000 and 2500 nm. The system is optimized for land applications including limnology, snow, and soil, amongst others. The instrument is optimized with various steps taken to allow for absolute calibrated radiance measurements. This includes the use of a pre- and post-data acquisition internal calibration facility as well as a laboratory calibration and a performance model serving as a stable reference. The instrument is currently in its breadboarding phase, including some new results with respect to detector development and design optimization for imaging spectrometers. In the same APEX framework, a complete processing and archiving facility (PAF) is developed. The PAF not only includes imaging spectrometer data processing up to physical units, but also geometric and atmospheric correction for each scene, as well as calibration data input. The PAF software includes an Internet based web-server and provides interfaces to data users as well as instrument operators and programmers. The software design, the tools and its life cycle are discussed as well.
The Optical Monitor Camera (OMC) is a part of the scientific payload being developed for the INTEGRAL mission, scheduled to be launched in 2001. The OMC is an imager that will monitor star variations in the V-band in a 5 X 5 degree field of view. An optical system based on 6 lenses has been developed in order to meet the optical requirements in specific environmental conditions. The concept of the optical system and the optical performances are discussed in this paper. The optical design was mainly driven by the high radiation levels and the very wide temperature range of the instrument. The system has been optimized with specific constrains: limited radiation resistant glasses availability and lens barrel material. The filter section is designed in order to improve the optical performances and to withstand the high radiation environment. Great care is taken for the tolerance analysis that is a key factor for the manufacturing process. Specific stray light analyses including ghost effects are included in the optical design.
The European Space Agency (ESA) has identified the necessity to initiate a study that concentrates on the definition of an airborne imaging spectrometer which could represent a precursor to the spaceborne PRISM. The study included the definition of an Airborne PRISM Experiment (APEX) that will contribute to the preparation, calibration, validation, simulation, and application development for the PRISM mission. The APEX instrument is defined as an airborne pushbroom imager with 1000 pixels across track and 200 user selectable spectral bands over the wavelength range from 450-2500 nm. The complete APEX system will include an aircraft, navigation data, laboratory and in-flight calibration as well as a data archiving and processing facility. The definition of the specifications of the APEX instrument is based on a sensor model taking into account various parameters of the expected operation range of the instrument. The approach used defines the radiometric properties of expected scene radiances including SNR and NE(Delta) (rho) . The APEX system is presented and in compliance with the PRISM instrument, conclusions on the simulation possibilities are derived and discussed.
The optical system of the critical point facility (CPF) was developed to investigate the behavior of fluids around their critical point. The fluids can be analyzed in four measurement channels: the visual, the interferometer and the small (SALS) and large (WALS) angle light scattering channels. During upgrading of CPF-IML1 for the IML2 Mission, special effort was made to improve the S/N ratio at minimum input signals and in consequence the absolute sensitivity of the small angel light scattering channel. The S/N ratio of the SALS channel was limited mainly by stray light from the surfaces and bulk materials of the optical components of the system and by the detector electronics. In the following the term 'scattered light' is used for the light scattered by the fluid and which has to be measured, and 'stray light' is the contribution of all other light sources disturbing the measurement. After the description of the optical system of CPF, modifications performed to improve the dynamic range of the SALS channel are described. The most important stray light sources are identified and ways to reduce their contribution to the noise are discussed. Modifications to improve the dynamic range of the SALS detector unit are described. Finally the consequences of the system upgrading activities on the optical performance of CPF are discussed.
Holographic Optical Elements (HOEs) are very appropriate for the construction
of Helmet Mounted Displays (HilDs).
The low weight and the compactness of HOEs allow for a design which meets the
mechanical specifications of a helmet much better than a design with classical
The weight of the optical system can be further reduced by using plastic
instead of glass substrates as support material for the holograms. If however,
the HOEs are recorded in dichromated gelatin, special precautions have to be taken
to obtain humidity-resistant HOEs and to ensure tight adhesion of the gelatin to
Furthermore, the influence of deformations of the substrate material on the image
quality has to be considered as well.
In order to find solutions for the above mentioned problems, DCG holograms
were recorded on the polycarbonate visor of holographic night vision goggles
(HNVG). To study the influence of the optical quality of the plastics on the
image quality of the HOEs, various recording configurations have been analyzed.