Dr. Jacques Loesel Profile

Dr. Jacques Loesel

Optical Engineer at Ctr National d'Études Spatiales

SPIE Involvement:

Author

Publications (17)

Proceedings Article | 12 July 2023 Open Access

Open Access

Paper

Convex blazed gratings for high throughput spectrographs in space missions

Frédéric Zamkotsian, Roger Krähenbühl, Patrick Lanzoni, Guillaume Basset, Michel Lequime, Myriam Zerrad, Claude Amra, Vincent Costes, Jacques Loesel

Proceedings Volume 12777, 127772J (2023) https://doi.org/10.1117/12.2689996

KEYWORDS: Blazed gratings, Optical gratings, Equipment, Spectrographs, Astronomical imaging, Reflection gratings, Optical surfaces, Spectroscopes, Diffraction gratings, Diffraction

Read Abstract +

In next generation space and ground-based instrumentation for Earth and Universe Observation, new instrument concepts include often non planar gratings. Their realization is complex and costly. We propose a new technology for designing and realizing convex blazed gratings for high throughput spectrographs. For this purpose, the requirements are driven by a Digital-Micromirror-Device-based (DMD) MOS instrument we are developing, called BATMAN. The two-arm instrument is providing in parallel imaging and spectroscopic capabilities. The objects/field selector is a 2048 x 1080 micromirrors DMD, placed at the focal plane of the telescope; it is used as a programmable multi-slit mask at the entrance of the spectrograph. The compact Offner-type spectrograph design contains a low density convex grating to disperse light. For optimization of the spectrograph efficiency, this convex grating must be blazed. A blazed reflective grating has been designed with a period of 3300 nm and a blaze angle of 5.04°, and fabricated into convex substrates with 225 mm radius of curvature and a footprint diameter of 63.5 mm. The blaze is optimized for the center wavelength of 580 nm within the spectral range of 400 – 800 nm. Such grating has been fabricated by using lithography, angular Ar ion etching, transfer of the blazed grating from a flat surface onto a convex substrate with a flexible stamp, etched into the substrate by RIE etching. and finally coated with a silver-based layer. With a final 7° blaze angle over the whole surface, efficiency close to 90% on the 1st diffraction order at 700nm has been obtained, measured on BATMAN spectroscopic arm. An optimized device with the exact required blaze angle would reach the same efficiency and be centered on the mid of 400-800nm wavelength band: its realization is on-going. The wavefront error of the diffracted beam will also be optimized. The grating brings a significant contribution in the total amount of straylight at instrument level. Their straylight level remains a critical issue, and its reduction by specific and controlled implementation of improvements in manufacturing process is a challenge to tackle. Straylight measurement has been done and shows a BRDF cosθ values of 10^-8 sr^-1 on the optical surface and 10^-7 sr^-1 on the structured features. This new type of non-planar reflective gratings will be the key component for future high throughput spectrographs in space missions

Proceedings Article | 29 August 2022 Presentation + Paper

Presentation + Paper

Blazed gratings on convex substrates for high throughput spectrographs

Frédéric Zamkotsian, Roger Krähenbühl, Patrick Lanzoni, Guillaume Basset, Michel Lequime, Myriam Zerrad, Claude Amra, Vincent Costes, Jacques Loesel

Proceedings Volume 12188, 1218824 (2022) https://doi.org/10.1117/12.2630045

KEYWORDS: Spectrographs, Diffraction gratings, Optical design, Diffraction, Digital micromirror devices, Bidirectional reflectance transmission function, Reflectivity, Imaging spectroscopy

Read Abstract +

In next generation space and ground-based instrumentation for Earth and Universe Observation, new instrument concepts include often non planar gratings. Their realization is complex and costly. We propose a new technology for designing and realizing convex blazed gratings for high throughput spectrographs. For this purpose, the requirements are driven by a Digital-Micromirror-Device-based (DMD) MOS instrument we are developing, called BATMAN. The two-arm instrument is providing in parallel imaging and spectroscopic capabilities. The objects/field selector is a 2048 x 1080 micromirrors DMD, placed at the focal plane of the telescope; it is used as a programmable multi-slit mask at the entrance of the spectrograph. The compact Offner-type spectrograph design contains a low density convex grating to disperse light. For optimization of the spectrograph efficiency, this convex grating must be blazed. A blazed reflective grating has been designed with a period of 3300 nm and a blaze angle of 5.04°, and fabricated into convex substrates with 225 mm radius of curvature and a footprint diameter of 63.5 mm. The blaze is optimized for the center wavelength of 580 nm within the spectral range of 400 – 800 nm. Such grating has been fabricated by using lithography, angular Ar ion etching, transfer of the blazed grating from a flat surface onto a convex substrate with a flexible stamp, etched into the substrate by RIE etching. and finally coated with a silver-based layer. With a final 7° blaze angle over the whole surface, efficiency close to 90% on the 1st diffraction order at 700nm has been obtained, measured on BATMAN spectroscopic arm. An optimized device with the exact required blaze angle would reach the same efficiency and be centered on the mid of 400-800nm wavelength band: its realization is on-going. The wavefront error of the diffracted beam will also be optimized. The grating brings a significant contribution in the total amount of straylight at instrument level. Their straylight level remains a critical issue, and its reduction by specific and controlled implementation of improvements in manufacturing process is a challenge to tackle. Straylight measurement has been done and shows a BRDF cosq values of 10-8 sr-1 on the optical surface and 10-7 sr-1 on the structured features. This new type of non-planar reflective gratings will be the key component for future high throughput spectrographs in space missions.

Proceedings Article | 11 June 2021 Open Access

Open Access

Presentation + Paper

Blazed gratings on convex substrates for high throughput spectrographs for Earth and Universe observation

Frédéric Zamkotsian, Igor Zhurminsky, Patrick Lanzoni, Nicolas Tchoubaklian, Fabian Lütolf, Marc Schnieper, Christian Schneider, Sören Fricke, Marin Fouchier, Myriam Zerrad, Claude Amra, Vincent Costes, Jacques Loesel

Proceedings Volume 11852, 118520N (2021) https://doi.org/10.1117/12.2599169

Read Abstract +

In next generation space instrumentation for Earth and Universe Observation, new instrument concepts include often non planar gratings. Their realization is complex and costly. We propose a new technology for designing and realizing convex blazed gratings for high throughput spectrographs. For this purpose, our requirements are driven by a Digital-Micromirror-Device-based (DMD) MOS instrument to be mounted on the Telescopio Nazionale Galileo (TNG) and called BATMAN. The two-arm instrument is providing in parallel imaging and spectroscopic capabilities. The objects/field selector is a 2048 x 1080 micromirrors DMD, placed at the focal plane of the telescope; it is used as a programmable multi-slit mask at the entrance of the spectrograph. The compact Offner-type spectrograph design contains a low density convex grating to disperse light. For optimization of the spectrograph efficiency, this convex grating must be blazed. A blazed reflective grating has been designed with a period of 3300 nm and a blaze angle of 5.04°, and fabricated into convex substrates with 225 mm radius of curvature and a footprint diameter of 63.5 mm. The blaze is optimized for the center wavelength of 580 nm within the spectral range of 400 – 800 nm. Such gratings have been fabricated and coated with a silver-based layer, with a final 7° blaze angle over the whole surface. Efficiency close to 90% on the 1st diffraction order at 700nm has been obtained, measured on BATMAN spectroscopic arm. Detailed mapping of the blazed grating showed a very good period uniformity with up to 0.5% deviation. Grating depth and blaze angle have higher deviation, up to 7%. An optimized device with the exact required blaze angle would reach the same efficiency and be centered on the mid of 400-800nm wavelength band: its realization is on-going. The grating brings a significant contribution in the total amount of straylight at instrument level. Their straylight level remains a critical issue, and its reduction by specific and controlled implementation of improvements in manufacturing process is a challenge to tackle. Preliminary straylight measurement has been done and shows a lowest straylight level below 10^-2 sr^-1 between the diffraction orders. This new type of non-planar reflective gratings will be the key component for future high throughput spectrographs in space missions.

Proceedings Article | 5 January 2018 Open Access

Open Access

Paper

Microcarb polarization scrambler

J. Loesel, M. Dubreuil, V. Pascal, C. Buil, F. Buisson

Proceedings Volume 10563, 1056318 (2018) https://doi.org/10.1117/12.2304241

KEYWORDS: Polarization, Phase shifts, Prisms, Tolerancing, Birefringence, Astronomical imaging, Spectroscopy, Sensors, Point spread functions, Atmospheric modeling

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Proceedings Article | 21 November 2017 Open Access

Open Access

Paper

PHARAO space atomic clock: new developments on the laser source

Muriel Saccoccio, Jacques Loesel, Claude Coatantiec, Eric Simon, Philippe Laurent, Pierre Lemonde, I. Maksimovic, M. Abgrall

Proceedings Volume 10568, 1056819 (2017) https://doi.org/10.1117/12.2307971

KEYWORDS: Cesium, Laser sources, Chemical species, Clocks, Semiconductor lasers, Atomic clocks, Microwave radiation, Bragg cells, Optical benches, Diodes

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Proceedings Article | 21 November 2017 Open Access

Open Access

Paper

Ion-plating metal-dielectric coatings for light absorbers

Frédéric Lemarquis, Michel Cathelinaud, Jacques Loesel, Bernard Cousin

Proceedings Volume 10568, 105681W (2017) https://doi.org/10.1117/12.2307990

KEYWORDS: Reflectivity, Dielectrics, Ions, Manufacturing, Metals, Opacity, Plating, Optics manufacturing, Optical coatings, Plasma

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Proceedings Article | 21 November 2017 Open Access

Open Access

Paper

Instrumental concept and preliminary performances of SIFTI: static infrared fourier transform interferometer

Philippe-Jean Hébert, E. Cansot, C. Pierangelo, C. Buil, F. Bernard, J. Loesel, T. Trémas, L. Perrin, E. Courau, C. Casteras, I. Maussang, D. Simeoni

Proceedings Volume 10566, 1056623 (2017) https://doi.org/10.1117/12.2308253

Read Abstract +

The SIFTI (Static Infrared Fourier Transform Interferometer) instrument aims at supporting an important part in a mission for atmospheric pollution sounding from space, by providing high spectral resolution and high Signal to Noise Ratio spectra of the atmosphere. They will allow to resolve tropospheric profiles of ozone (0₃) and carbon monoxide (C0), especially down to the planetary boundary layer (PBL), an altitude region of very high interest, though poorly monitored to date, for air quality and pollution monitoring. The retrieved profile of ozone, resp. C0, will contain 5 to 7, resp. 2.5 to 4, independent pieces of information.

The French space agency CNES (Centre National d'Etudes Spatiales) has proposed and is studying an instrument concept for SIFTI based on a static interferometer, where the needed optical path are generated by a pair of crossed staircase fixed mirrors (replacing the moving reflector of dynamic Fourier transform interferometers like IASI or MIPAS). With the SIFTI design, a very high spectral resolution (~0.1 cm^-1 apodised) is achieved in a very compact optical setup, allowing a large throughput, hence a high SNR. The measurements are performed in the 9.5 μm band for 03 and in the 4.6 μm band for C0.

The science return of the sounder can be further increased if an "intelligent pointing" process is implemented. This consists in combining the TIR sounder with a companion TIR imager, providing information on the cloud coverage in the next observed scene. 0nboard, real-time analysis of the IR image is used to command the sounder staring mirror to cloud free areas, which will maximize the probability for probing down to the surface. After the first part of the phase A, the architecture of SIFTI was studied as a trade-off between performance and resource budget. We review the main architecture and functional choices, and their advantages. The preliminary instrument concept is then presented in its main aspects and in terms of main subsystem functions.

The preliminary budgets of mass, volume, size and power are also evaluated. Eventually the science performances are estimated, at instrument level and at mission level, and are compared to the specifications. To finish, the ways forward are discussed.

Proceedings Article | 21 November 2017 Open Access

Open Access

Paper

Optical design of PHARAO

Jacques Loesel, Jacques Berthon, Muriel Saccoccio, Nathalie Raimbault, Yvan Aubry, André Clairon, Philippe Laurent, Pierre Lemonde

Proceedings Volume 10569, 105690T (2017) https://doi.org/10.1117/12.2307894

KEYWORDS: Chemical species, Cesium, Laser sources, Semiconductor lasers, Atomic clocks, Bragg cells, Diffraction, Resonators, Optical benches, Optical design

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Proceedings Article | 21 November 2017 Open Access

Open Access

Paper

New optical technology for cold atom experiments

D. Holleville, N. Dimarcq, F. Rigaud, M. Saccoccio, J. Berton, J. Loesel, C. Chappaz, M. De Labachelerie, J. Valentin, S. Bonnefont, P. Arguel, F. Lozes, F.-J. Vermersch, M. Krakowski

Proceedings Volume 10568, 105680V (2017) https://doi.org/10.1117/12.2308004

KEYWORDS: Chemical species, Atomic clocks, Semiconductor lasers, Clocks, Quartz, Optical benches, Laser sources, Beam splitters, Optical components, Cesium

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Proceedings Article | 20 November 2017 Open Access

Open Access

Paper

A new space instrumental concept based on dispersive components for the measurement of CO2 concentration in the atmosphere

Véronique Pascal, Christian Buil, Elodie Cansot, Jacques Loesel, Laurie Tauziede, Clémence Pierangelo, François Bermudo

Proceedings Volume 10564, 105641R (2017) https://doi.org/10.1117/12.2309052

Read Abstract +

Measuring the concentration of greenhouse gases from space is a current challenge. This measurement is achieved via a precise analysis of the signature of chemical gaseous species (CO2, CH4, CO, etc.) in the spectrum of the reflected sunlight. First at all, two families of spectrometers have been studied for the MicroCarb mission. The first family is based on the phenomena of interference between two radiation waves (Michelson Interferometer). The second family is based on the use of dispersive optical components. The second family has been selected for the forthcoming studies in the MicroCarb project. These instruments must have high radiometric and spectral resolutions, in narrow spectral bands, in order to discriminate between absorption lines from various atmospheric chemical species, and to quantify their concentration. This is the case, for example, for the instrument onboard the OCO-2 satellite (NASA/JPL).

Our analysis has led us to define a new instrumental concept, based on a dispersive grating spectrometer, with the aim of providing the same accuracy level as the OCO-2, but with a more compact design for accommodation on the Myriade Evolution microsatellite class. This compact design approach will allow us to offer a moderate-cost solution to fulfil mission objectives. Two other studies based on dispersive grating are in progress by CNES prime contractors (ASTRIUM and THALES ALENIA SPACE).

A summary of the main specifications of this design will be described, in particular the approach with the so-called “merit function”. After a description of such a space instrument, which uses a specific grating component, a preliminary assessment of performances will be presented, including the theoretical calculations and formula. A breadboard implementation of this specific grating has allowed us to show the practicality of this concept and its capabilities. Some results of this breadboard will be described. In addition, an instrument simulator is being developed to validate the performances of this concept. A grating component prototype has been built, and the specifications, together with the expected performances, will be described, in particular the polarisation ratio. Some elements about detectors will be also given regarding their suitability for the mission. This preliminary design is encouraging and shows that such a spectrometer may be compatible with a microsatellite platform (low mass, low power and compact design). Some prospects of improvements will also be considered.

Proceedings Article | 17 November 2017 Open Access

Open Access

Paper

An improved microcarb dispersive instrumental concept for the measurement of greenhouse gases concentration in the atmosphere

V. Pascal, C. Buil, J. Loesel, L. Tauziede, D. Jouglet, F. Buisson

Proceedings Volume 10563, 105633K (2017) https://doi.org/10.1117/12.2304219

KEYWORDS: Sensors, Spectroscopy, Polarization, Carbon monoxide, Spectral resolution, Diffraction gratings, Multiplexing, Telescopes, Diffraction, Gases

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Proceedings Article | 4 October 2011 Paper

Paper

A new space instrumental concept for the measurement of CO2 concentration in the atmosphere

Christian Buil, Véronique Pascal, Jacques Loesel, Clémence Pierangelo, Lionel Roucayrol, Laurie Tauziede

Proceedings Volume 8176, 817621 (2011) https://doi.org/10.1117/12.897598

KEYWORDS: Carbon dioxide, Spectroscopy, Sensors, Diffraction, Diffraction gratings, Satellites, Signal to noise ratio, Spectral resolution, Error analysis, Earth's atmosphere

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Proceedings Article | 27 September 2008 Paper

Paper

Study of accessible performances of a spectro imager using a wedge filter

Jacques Loesel, David Laubier

Proceedings Volume 7100, 710013 (2008) https://doi.org/10.1117/12.796966

KEYWORDS: Optical filters, Sensors, Stray light, Optical filtering, Imaging systems, Coating, Reflection, Linear filtering, Charge-coupled devices, Image filtering

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Proceedings Article | 27 September 2008 Paper

Paper

Static Fourier transform spectroscopy breadboards for atmospheric chemistry and climate

Frank Brachet, Philippe-Jean Hébert, Elodie Cansot, Christian Buil, Antoine Lacan, Lionel Roucayrol, Etienne Courau, Frédéric Bernard, Christophe Casteras, Jacques Loesel, Clémence Pierangelo

Proceedings Volume 7100, 710019 (2008) https://doi.org/10.1117/12.797686

KEYWORDS: Mirrors, Carbon dioxide, Calibration, Fourier transforms, Infrared radiation, Thermography, Interferometry, Atmospheric chemistry, Beam splitters, Spectroscopy

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Proceedings Article | 21 October 2005 Paper

Paper

Long quadrilinear CCD sensors equipped with long linear filters: characteristics and performances for the multispectral channel of Earth observing systems

Herve Geoffray, Jacques Loesel, Isabelle Loiret, Jean-Jacques Quicot

Proceedings Volume 5978, 597814 (2005) https://doi.org/10.1117/12.628226

KEYWORDS: CCD image sensors, Charge-coupled devices, Optical filters, Sensors, Linear filtering, Prototyping, Interfaces, Stray light, Calibration, Signal to noise ratio

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Proceedings Article | 25 February 2004 Paper

Paper

Metal-dielectric light absorbers manufactured by ion plating

Michel Cathelinaud, Frederic Lemarquis, Jacques Loesel, Bernard Cousin

Proceedings Volume 5250, (2004) https://doi.org/10.1117/12.513409

KEYWORDS: Dielectrics, Reflectivity, Ions, Manufacturing, Metals, Plating, Opacity, Plasma, Transmittance, Hafnium

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Proceedings Article | 18 February 2004 Paper

Paper

A highly stable frequency stabilized extended cavity diode laser for space

Eric Simon, Claude Coatantiec, Muriel Saccoccio, Didier Blonde, Jacques Loesel, Phillipe Laurent, Ivan Maksimovic, Michel Abgrall

Proceedings Volume 5249, (2004) https://doi.org/10.1117/12.515363

KEYWORDS: Semiconductor lasers, Clocks, Cesium, Diodes, Fabry–Perot interferometers, Bragg cells, Ferroelectric materials, Absorption, Optical filters, Chemical species

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Showing 5 of 17 publications

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