In the field of failure analysis and in particular molecular and particulate contamination, being able to detect any trace of contaminants during the integration of an orbital spacecraft is crucial. In this context, fluorescence allows not only to detect but also to discriminate contaminants. We studied the fluorescence response of two epoxy adhesives, typical sources of spacecraft contamination in orbit with a portable broadband hyperspectral instrument (UV-Vis-NIR) developed in collaboration with the CNES and Intraspec Technologies, but also with a commercial spectrofluorometer. These measurements had two objectives, evaluate the performance of our hyperspectral instrument in order to identify prospect of improvement, but as well study the pertinence of fluorescence signature study in the contamination field. The first goal brings out that the hyperspectral instrument is capable of imaging the scene and allows us to extract fluorescence spectra from the image, but it still needs development, especially in term of sensitivity in UV range. The second goal shows promising results. Fluorescence studies with the spectrofluorometer emphasize that fluorescence spectra are specific to the chemical nature of the contaminant, which allows us to clearly discriminate them.

Thanks to a large set of available photocathodes with first in class QE, high gain, high collection efficiency, high dynamic range while keeping low dark count rate and single photon resolution capability with excellent timing, MCP-PMTs have emerged as candidates for LIDAR receivers.We present results of Ageing tests and Radiation tests carried out with Photonis and Airbus Defence & Space on High QE, and High linearity MCP-PMT for UV LIDAR receivers.Ageing of the photocathode is usually due to electron-induced ion feedback and molecule desorption from the MCP and anode, causing degradation of the photocathode layer leading to a progressive loss of QE related to the quantity of electron charges generated along lifetime.Expected Coulomb charges generated along a typical and worst-case mission were estimated from the atmosphere profiles.Thanks to a design change of the MCP-PMT and the implementation of Long-Lifetime MCP technology, ageing of the photocathode was drastically reduced.The new design showed no Quantum Efficiency nor Collection Efficiency degradation up to 20 C. Proton radiation tests were performed to evaluate false signal generated, end-of-life impact on performance, loss of transmission depending on the photocathode glass substrate as well as cathodoluminescence and photoluminescence at the photocathode.Quantum Efficiency, Collection Efficiency, PHD shape, Gain, and Linearity were found to be unchanged for fluences of 5x10 11 p+/cm² with 60 MeV protons.Only small increase of DCR for about 120 cps/cm² was recorded about 8 weeks after the radiation.

In space applications, more and more organic polymers (adhesives, resins, paints and packaging of electronic devices) are used for their performance, their cost and their flexibility for the design of future satellites. This is especially true in the New Space era, using Off-The-Shelf devices with rarely well-known materials. Outgassed products of these materials under vacuum is a major cause of dramatic flux losses for contaminated optical devices, especially in the UV range. Thus, material outgassing must be studied and better controlled, during all the phases of satellite integration. Fluorescence hyperspectral imaging is a powerful technique for both locating and analyzing materials: their fluorescence spectra can be interpreted as a signature of their physicochemical composition. However, common commercial hyperspectral instruments do not meet the specifications required for such applications: very high sensitivity (SNR > 10000), wide spectral band (ideally 250-1000 nm), integrated multi-wavelength UV excitation and spectral range resolution of about 3 nm. In addition, classical optical design with diopters has to be avoided to prevent chromaticism, which is not compatible with wide spectral bandwidth, especially in UV range. These constraints led us to develop a new dedicated optical design, with the specificity of being catoptric on axis. Therefore, we built a first transportable instrument. In this paper, we present the evaluation of the characteristics of this instrument, its real performance and examples of measurements on flight models. A new version has been designed, using laser sources to limit exposure time of examined materials as much as possible, as they may be degraded under UV light.

This article describes the qualification process for a 1.8 kW laser diode stack designed for the Mars Curiosity rover. The seven-bar stack serves as the optical pump in a boom-mounted spectroscope attached to the front of the rover. Each laser bar is made of 62 single emitters and generates 260 W of instantaneous optical power. A detailed design analysis of the diode stack is presented along with the results of overstress testing and failure analysis.

Standard space solar arrays consist of solar cells protected by coverglass, glued individually on rigid substrate. The solar cells / substrate bonding interface quality is crucial since trapped air bubbles at this interface can cause strong cell damages once under vacuum. In this study, we show that transient electroluminescence can be used as a fast and non-destructive characterization tool to map the solar cells rear-side gluing interface defects.

The increase of performance of new optical instruments for science and Earth observation always leads to higher requirements in terms of contamination due to particle sedimentation in cleanrooms and deposition of chemical species in vacuum environment. Specific cleanliness control procedures are implemented in order to mitigate the risks of contamination on optical sensors and sensitive diopters, especially when used for UV applications. Such procedures are commonly carried out in cleanrooms and are described in both European ECSS-Q-ST-70-50C and NASA SN-C-0005D standards. UV light at 365 nm is often used for the inspection of optical sensitive surfaces to localize and to evaluate the amount of fluorescent particles, essentially coming from textile fibers. But other groups of compounds can be observed with a different spectral response and distribution, like adhesives and resins or even organic residues. Therefore, we could take advantage of this spectral information closely linked to specific molecules for partial identification of these materials before further investigation involving wipe on flight model and measurement in a laboratory.

Optical instruments for space applications with improved performances (smaller pixels and spectral range extension) are becoming more and more sensitive to chemical contamination and particle sedimentation. Outgassing under vacuum conditions causes dramatic flux losses, especially in the UV bandwidth.Furthermore, it is difficult to perform physicochemical analyses of contaminated surfaces on flight models, in a clean room. Conventional analytical techniques such as FTIR (Fourier Transform Infrared interferometer) need the tool to be in contact with the studied area, which is forbidden when working on satellites. In addition, it does not give any information about the distribution of the contaminants in the field of view. The probed area is large, mono-pixel, and the sensitivity of the instrument is too low for hundred nanometer thin film deposits.A first study has shown that we could benefit from using the UV/visible fluorescence spectra to partially identify contaminants and polymer materials. The shape of the fluorescence spectra of adhesives, paints and varnishes have specific signatures that could be recorded into a designated reference database. The location of the presence of these contaminants on such sensitive optics is also relevant.To acquire both these parameters, we designed a specific compact hyperspectral instrument to remotely acquire cube images (500x500 pixels) in a 5 degree field of view, and on a wide range of continuous wavelengths from UV at 320 nm up to the near infrared at 1000 nm.This paper will present the chosen trade-off between different critical optics for a new portable version of this instrument. It is dedicated to space and cultural heritage applications and the first results on an engineering prototype will be shown.

Failure analysis on optical components is usually carried-out, on standard testing devices such as optical/electronic microscopes and spectrometers, on isolated but representative samples. Such analyses are not contactless and not totally non-invasive, so they cannot be used easily on flight models. Furthermore, for late payload or satellite integration/validation phases with tight schedule issues, it could be necessary to carry out a failure analysis directly on the flight hardware, in cleanroom.

In this paper, we propose a new method to evaluate the thermal resistance of laser diodes and light emitting diodes based on the analysis of common emitter characteristics (emission spectrum, power–current and voltage–current characteristics) measured in CW condition. This method has been used to assess the thermal resistance of commercial GaAlAs laser and light emitting diodes emitting at 780 nm and 872 nm respectively. Finally, the method is compared with classic threshold current method carried out on the laser diodes.

Laser stimulation techniques are continuously developed in accordance with the apparition of new kind of defect. We propose the full dynamic laser stimulation where the test is fully embedded in the localization process. By using a modulated laser instead of a continuous one we discriminate vectors fail in addition to localization.

The development of new high power EUV sources and EUV space imaging requires optics having specific properties which depend on applications and operating conditions. These both applications are very different in the working multilayers environment. For the high power sources, multilayers are submitted to short pulses with high energy peak whereas, for the space imaging, multilayers are submitted to continuous flux with low level. Moreover photon energy and environment for both applications may be different. The environment may affect structure and top layer contamination when optics are stored, handled, mounted on the final device and finally operating. Main environmental parameters investigated are temperature and humidity variation.One objective is the optimisation of multilayer coatings to offer the highest resistance under photonic, ionic fluxes and temperature cycle. This means that interfacial diffusion between thin layers and degradation of the capping layers have to be avoided or reduced. The present study relies with designing, depositing and testing different structures of multilayer coatings in order to minimise the influence of the environment. Multilayer coatings based on molybdenum, silicon and silicon carbide materials have been deposited by magnetron sputtering on silicon and zerodur substrates. Samples were submitted to radiations emitted by an EUV source at wavelength closed to 13.5 nm. Furthermore they were also submitted to thermal cycles and annealing under warm humidity in the aim to simulate extremes storage or handling conditions as space mission's conditions.The damages and the performance of the multilayers were evaluated by using grazing incidence reflectometry at 0.154 nm and EUV reflectometry at the operating wavelength. After a presentation of the multilayer design, deposition and metrology tools, we will describe the different environmental effects on the coatings to take in care during EUV source exposure, handling and storage conditions. First results on multilayers performances to EUV source exposure and space specification tests are presented. Main damages studies were on annealing, thermal cycling and warm humidity.