We present a ground-to-space quantum key distribution (QKD) mission concept and the accompanying feasibility study for the development of the low earth orbit CubeSat payload. The quantum information is carried by single photons with the binary codes represented by polarization states of the photons. Distribution of entangled photons between the ground and the satellite can be used to certify the quantum nature of the link: a guarantee that no eavesdropping can take place. The versatile space segment is compatible with a multiple of QKD protocols, as well as quantum physics experiments.
Direct imaging systems are now designed for specific telescope apertures and specific high-contrast diffraction 2D patterns. Current coronagraphic masks are not adaptive components, and different apertures and science requirements must result in different masks, which always come in a small number in a real-life instrument. Adaptive components would make it possible to adapt to changes in the aperture transmission (which will likely happen on a daily basis with the near future highly segmented telescopes, such as ESO's ELT), as well as to reconfigure at will the high-contrast area for different observation modes. In particular, the prospect of characterizing planets with a known position at a high spectral resolution pushes for adaptive coronagraphs capable of creating high-contrast in a small area of the image plane. Micro-mirror arrays are commercially available MOEMS that may be used as binary adaptive amplitude mask. They adaptively redirect light in either one of two directions using millions of micron-sized, bi-stable mirrors. Their spatial resolutions is compatible with 2D binary apodization patterns, in addition to Lyot stops. We have conducted a series of laboratory tests to assess the compatibility of an off-the-shelf micro-mirror array with high-contrast imaging requirements. This communication first presents the context and the scope of the project. It then details the results of our initial characterization of the device, in particular a measurement of the wavefront aberrations and of the level of scattered light that it introduces. Finally, it presents high-contrast point-spread functions obtained with this device, and summarizes the limitations of current components to derive a possible roadmap for the development of scientific-grade adaptive pupil masks.
High-resolution spectroscopy is a key element for present and future astronomical instrumentation. In particular, coupled to high contrast imagers and coronagraphs, high spectral resolution enables higher contrast and has been identified as a very powerful combination to characterise exoplanets, starting from giant planets now, up to Earth-like planet eventually for the future instruments. In this context, we propose the implementation of an innovative echelle spectrometer based on the use of VIPA (Virtually Imaged Phased Array, Shirasaki 1996). The VIPA itself is a particular kind of Fabry-P´erot interferometer, used as an angular disperser with much greater dispersive power than common diffraction grating. The VIPA is an efficient, small component (3 cm × 2.4 cm), that takes the very advantage of single mode injection in a versatile design. The overall instrument presented here is a proof-of-concept of a compact, high-resolution (R > 80 000) spectrometer, dedicated to the H and K bands, in the context of the project “High-Dispersion Coronograhy“ developed at IPAG. The optical bench has a foot-print of 40 cm × 26 cm ; it is fed by two Single-Mode Fibers (SMF), one dedicated to the companion, and one to the star and/or to a calibration channel, and is cooled down to 80 K. This communication first presents the scientific and instrumental context of the project, and the principal merit of single-mode operations in high-resolution spectrometry. After recalling the physical structure of the VIPA and its implementation in an echelle-spectrometer design, it then details the optical design of the spectrometer. In conclusion, further steps (integration, calibration, coupling with adaptive optics) and possible optimization are briefly presented.
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 this communication we present the first experimental results obtained on the Crossed-cubes nuller (CCN), that is a new type of Achromatic phase shifter (APS) based on a pair of crossed beamsplitter cubes. We review the general principle of the CCN, now restricted to two interferometric outputs for achieving better performance, and describe the experimental apparatus developed in our laboratory. It is cheap, compact, and easy to align. The results demonstrate a high extinction rate in monochromatic light and confirm that the device is insensitive to its polarization state. Finally, the first lessons from the experiment are summarized and discussed in view of future space missions searching for extrasolar planets located in the habitable zone, either based on a coronagraphic telescope or a sparse-aperture nulling interferometer.