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Scheid B.,Roosevelt University | Margerit J.,University of Liège | Iorio C.S.,Roosevelt University | Joannes L.,Lambda X | And 4 more authors.
Experiments in Fluids | Year: 2012

The dynamics of thermal ripples at the interface of a volatile pure liquid (C 2H 5OH) is studied experimentally and numerically. Liquid evaporates under a flow of inert gas (N 2) circulating along the interface. The evaporation rate is varied by regulating both the gas flow rate and the gas pressure. Experiments in microgravity environment allowed to identify a transition to ''interfacial turbulence,'' along which some particular events such as nearly periodic and possible intermittent behaviors. Direct numerical simulations have been performed, and compare qualitatively well with experimental results, offering new insights into the physical mechanisms involved. Smallscale ripples appear to arise from a secondary instability of large-scale convection cells and their motion seems to follow the corresponding large-scale surface flow. The relative role of surface tension and buoyancy in triggering these flows is assessed by comparing experiments and simulations in both microgravity and ground conditions. Qualitative features compare satisfactorily well such as typical speed and orientation of the thermal ripples, as well as spiral flow in the bulk. © Springer-Verlag 2011.


De Vos W.H.,University of Antwerp | De Vos W.H.,Ghent University | Beghuin D.,Lambda X | Schwarz C.J.,European Space Agency | And 4 more authors.
Review of Scientific Instruments | Year: 2014

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as ionizing radiation and microgravity at the cellular and tissue level demands adequate visualization technology. Advanced light microscopy (ALM) is the leading tool for non-destructive structural and functional investigation of static as well as dynamic biological systems. In recent years, technological developments and advances in photochemistry and genetic engineering have boosted all aspects of resolution, readout and throughput, rendering ALM ideally suited for biological space research. While various microscopy-based studies have addressed cellular response to space-related environmental stressors, biological endpoints have typically been determined only after the mission, leaving an experimental gap that is prone to bias results. An on-board, real-time microscopical monitoring device can bridge this gap. Breadboards and even fully operational microscope setups have been conceived, but they need to be rendered more compact and versatile. Most importantly, they must allow addressing the impact of gravity, or the lack thereof, on physiologically relevant biological systems in space and in ground-based simulations. In order to delineate the essential functionalities for such a system, we have reviewed the pending questions in space science, the relevant biological model systems, and the state-of-the art in ALM. Based on a rigorous trade-off, in which we recognize the relevance of multi-cellular systems and the cellular microenvironment, we propose a compact, but flexible concept for space-related cell biological research that is based on light sheet microscopy. © 2014 AIP Publishing LLC.


De Vos W.H.,Ghent University | Meesen G.,Ghent University | Szpirer C.,Delphi Corporation | Scohy S.,Delphi Corporation | And 4 more authors.
Planetary and Space Science | Year: 2012

A major concern for long-term deep space missions is the detrimental impact of cosmic radiation on human health. Especially the presence of high-energy particles of high atomic mass (HZE) represents a serious threat. To contribute to a fundamental understanding of space radiation effects and to help improving risk assessment for humans on the Moon, the ESA Lunar Lander mission model payload includes a package dedicated to cell-based radiobiology experiments in the form of an Autonomous Microscope for Examination of Radiation Effects (AMERE). The purpose of this setup is to enable real-time visualization of DNA damage repair in living cells after traversal of HZE particles on the Moon. To assess the feasibility of this challenging experiment, we have analysed the biological and technological demands. In this article, we discuss the experimental concept, the biological considerations and describe the implications for system design. © 2012 Elsevier Ltd. All rights reserved.


Patent
Lambda X | Date: 2012-12-19

Described herein is an optical system (100) for reducing the effects of speckle in an interferometer system. The system (100) comprises a laser array (110), intermediate optics (120), a diffuser (130), an integrator (140), and a projection lens system (150) comprising first and second light projection lenses (160, 170) with and an aperture (180) located therebetween. The integrator (140) comprises a uniform output face (190) which can be considered to be a secondary source that is very homogeneous in intensity. The secondary source has been shown to have low speckle contrast whilst retaining high temporal coherence. The low speckle contrast is inversely proportional to the number of laser emitters in the laser array (110) and therefore a vertical cavity surface emitting laser is the preferred laser array as at least 1000 individual emitters can be provided in one device.


Patent
Lambda X | Date: 2014-01-24

Described herein is a hyperspectral imaging system in which a polarising beam splitter, a Wollaston prism, an optical system, and a plane mirror are arranged on an optical axis of the imaging system. An imaging detector is provided on which radiation is focused by an imaging lens. The Wollaston prism is imaged on itself by the optical system and the plane mirror so that translation of the Wollaston prism in a direction parallel to a virtual split plane of the prism effectively provides an optical path length difference that is the same for all points in the object field.


Patent
Lambda X | Date: 2014-04-23

Described herein is an angular position sensing system (100) and method for determining the angular position of a punctual radiating source (130) with respect to a linear sensor element (110). The linear sensor element (110) having a surface (115) comprising a discrete set of pixels. A periodic grating (120) is provided over the surface (115) of the linear sensor element (110) and the output from each pixel in the discrete set of pixels produces a periodic output signal (140), the phase of which is representative of an angle () of radiation from the radiating source (130) with respect to the linear sensor element (110). The periodic output signal (140) is processed in the analogue domain to provide quadrature output signals (190, 195).


PubMed | University of Marburg, University of Antwerp, Goethe University Frankfurt, Lambda X and 2 more.
Type: Journal Article | Journal: The Review of scientific instruments | Year: 2014

As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as ionizing radiation and microgravity at the cellular and tissue level demands adequate visualization technology. Advanced light microscopy (ALM) is the leading tool for non-destructive structural and functional investigation of static as well as dynamic biological systems. In recent years, technological developments and advances in photochemistry and genetic engineering have boosted all aspects of resolution, readout and throughput, rendering ALM ideally suited for biological space research. While various microscopy-based studies have addressed cellular response to space-related environmental stressors, biological endpoints have typically been determined only after the mission, leaving an experimental gap that is prone to bias results. An on-board, real-time microscopical monitoring device can bridge this gap. Breadboards and even fully operational microscope setups have been conceived, but they need to be rendered more compact and versatile. Most importantly, they must allow addressing the impact of gravity, or the lack thereof, on physiologically relevant biological systems in space and in ground-based simulations. In order to delineate the essential functionalities for such a system, we have reviewed the pending questions in space science, the relevant biological model systems, and the state-of-the art in ALM. Based on a rigorous trade-off, in which we recognize the relevance of multi-cellular systems and the cellular microenvironment, we propose a compact, but flexible concept for space-related cell biological research that is based on light sheet microscopy.


Sudhakar P.,Catholic University of Leuven | Jacques L.,Catholic University of Leuven | Dubois X.,Lambda X | Antoine P.,Lambda X | Joannes L.,Lambda X
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2013

Schlieren deflectometry aims at characterizing the deflections undergone by refracted incident light rays at any surface point of a transparent object. For smooth surfaces, each surface location is actually associated with a sparse deflection map (or spectrum). This paper presents a novel method to compressively acquire and reconstruct such spectra. This is achieved by altering the way deflection information is captured in a common Schlieren Deflectometer, i.e., the deflection spectra are indirectly observed by the principle of spread spectrum compressed sensing. These observations are realized optically using a 2-D Spatial Light Modulator (SLM) adjusted to the corresponding sensing basis and whose modulations encode the light deviation subsequently recorded by a CCD camera. The efficiency of this approach is demonstrated experimentally on the observation of few test objects. Further, using a simple parameterization of the deflection spectra we show that relevant key parameters can be directly computed using the measurements, avoiding full reconstruction. © 2013 IEEE.

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