Category Archives: KERNEL

My Innovation Is…

A few months ago, I heard about an innovation contest organized by SATT Sud-Est, a company that attempts to facilitate the transfer of technology from laboratories to the industry. The application process looked simple enough so I gave it a shot. It turns out that my application: basically a pitch for robust high-contrast instrumentation (aka a kernel-nuller), was among the ten selected for a live oratory contest that was held just a few days ago, in the city of Avignon inside the famous “Palais des Papes“.

Without direct industrial prospect for the kernel-nuller, it is no surprise that my pitch was not selected as the final winner. The awards went to Dr. Christine Contino-Pepin and Pr. Michel Alain Bartoli who will I have no doubt, be able to turn their ideas into profitable businesses!

Nevertheless, this was a lovely evening, and according to the feedback I received during the networking event that followed, attendees were quite intrigued and enthusiastic about the project. This is the real magic of astronomy in general and of extrasolar planets in particular that still manage to trigger people’s imagination. Even if science in general isn’t the most popular topic of conversation out there, public conferences about astronomy still manage to draw reasonably large and passionate crowds! If only we could trigger the same kind of amazement for all of the other sciences, the world would certainly be a better place!

Habilitation à Diriger des Recherches… soutenue!

Page de garde de la présentation HDR de Frantz

Le jeudi 4 octobre 2018 à l’Observatoire de la Côte d’Azur, j’ai enfin pu soutenir ma thèse d’habilitation à diriger des recherches (HDR), intitulée: “Repousser les limites de la diffraction pour l’astronomie à haute résolution angulaire”.

Parlez vous SCExAO? Présentation des différents avatars des outils graphiques de contôle de SCExAO

Après une (un peu trop longue?) présentation de mon travail de recherche depuis la soutenance de ma thèse de doctorat, en juillet 2005 et une série de questions, le jury composé de:

  • Jean Surdej, Université de Liège (Président du jury)
  • David Mouillet, IPAG (Rapporteur)
  • David Mary, Université de Nice Sophia-Antipolis (Rapporteur)
  • Olivier Guyon, Université d’Arizona (Rapporteur)
  • Jean François Sauvage, ONERA Chatillon (Examinateur)
  • Anthony Boccaletti, Observatoire de Paris (Examinateur)
  • Farrokh Vakili, Observatoire de la Côte d’Azur (Examinateur)

m’a fait l’honneur de me décerner l’habilitation à diriger des recherches en sciences… voilà une bonne chose de faite!

Devant le transparent de conclusion de la soutenance, de gauche à droite: Jean-François Sauvage, Anthony Boccaletti, Jean Surdej, Farrokh Vakili, David Mary, Frantz Martinache, Olivier Guyon et David Mouillet


Le fichier de ma présentation (beamer PDF) compilé depuis org-mode de Emacs peut être téléchargé depuis ma page web (30 Mb)!

Kernel-nulling paper accepted for publication by Astronomy & Astrophysics

It is my great pleasure to be able announce that the paper Mike Ireland (ANU) and I wrote, entitled “Kernel-nulling for a robust direct interferometric detection of extrasolar planets” has been accepted for publication by Astronomy & Astrophysics.

The paper introduces a baseline class of nulling-interferometers producing outputs that can be robustly calibrated. These new observable quantities exhibit properties that are similar to closure- and kernel-phase, while taking advantage of the use of a true nulling stage. The first version of our paper had been previously announced. The (updated) preprint of the paper is now available on arXiv.

It is fantastic to have this piece accepted: the quest for robust high-contrast solutions has been on my mind for a while… And now that we know that at least one solution exists, surely others must do too!

Conclusion slide from a presentation I gave, describing Kernel-nulling and the VIKiNG instrument concept it leads to for VLTI.

Postdoctoral position in Astronomical Instrumentation for the KERNEL project

Schematic representation of an early design of the KERNEL test-bench


The KERNEL project, hosted by Observatoire de la Cote d’Azur (OCA) invites applications for a postdoctoral research position in the field of high-angular resolution astronomy starting no later than February 1, 2019. This position is funded by the European Research Council (ERC – CoG – grand agreement #683029) under the European Union’s Horizon 2020 research and innovation program.

The KERNEL project

KERNEL aims at enabling every optical and infrared astronomical facility to reach its ultimate angular resolution potential, often pushing beyond the formal diffraction limit, while preserving the full sensitivity. By looking at astronomical data as the result of an interferometric process, the KERNEL framework brings much needed robustness to high-performance observing techniques, required for instance for the direct detection of extrasolar planets.

The mission

The KERNEL framework offers a wide range applications that go from the post-processing of available archival data to high-performance focal plane metrology, partly coupled with high-contrast imaging. In order to develop and prototype the next generation of high-performance instruments and metrology monitoring tools for ground based telescopes and interferometers, the completion of the KERNEL project includes the construction of a general purpose test-bench, with elements that have already been successfully deployed for on-sky applications. The postdoc responsibility will be to oversee the completion of this KERNEL test-bench.

The test-bench primarily relies on a high-order segmented deformable mirror used to modulate the phase across a diffractive aperture and a high-cadence low-readout near-infrared camera, simultaneously in up to four complementary spectral bandpasses.

The multi-band aspect of the bench expands on the capability already offered by the KERNEL framework:

  • it extends the range of tolerated input instrumental phase, with applications such fringe tracking for long baseline interferometry and adaptive optics for large telescopes.
  • it provides further calibration capability, allowing for the acquisition of spectral differential kernel-phases

In addition, with its simple but agile high-contrast mode, the bench will also make it possible to experimentally validate observing strategies devised in the context of the project that bring robustness to aberrations to high-contrast direct detection.

How to apply

A Ph.D. in astronomy, physics, or a closely related field is mandatory. We are interested in individuals with several years of post-PhD research experience in the development and the scientific exploitation of instrumentation in the field of high angular resolution astronomy that include active wavefront compensation either in the laboratory or at the telescope. The candidate should be willing to collaborate with and assist graduate students that will use the KERNEL bench for their research projects. The candidate will also be encouraged to take advantage of the experimental setup and the KERNEL project members expertise to pursue his/her own research interests.

The candidate must also possess a strong background in the modeling, reduction and interpretation of diffraction dominated data (interferograms and/or AO-corrected images). Experience with the Python and/or the C programming language is highly desirable.

The initial appointment will be for two years, with possible extensions up to four years. The successful candidate will be hosted by the Lagrange Laboratory, with a lab located on the campus of Valrose, downtown the beautiful city of Nice, France.

To apply, please send a copy of your curriculum vitae, and a summary of your research interests. Also arrange for three reference letters to be sent to Frantz Martinache ( For full consideration, applications should be received before September 15, 2018, although applications will be reviewed up until the position is filled.

PhD in Astronomical Instrumentation for the KERNEL project: focal plane based extreme adaptive optics

The KERNEL project, hosted by Observatoire de la Cote d’Azur (OCA) invites applications for a PhD project in the field of high-angular resolution astronomy. This position is funded by the European Research Council (ERC – CoG – grand agreement #683029) under the European Union’s Horizon 2020 research and innovation program. The add was also posted on EURAXESS.

The adaptive optics revolution

Adaptive Optics (AO) has changed the face of observational astronomy, making ground based telescope able to live up to their angular resolution potential, and allowing us to dream up the upcoming generation of large 30m-class giant segmented mirror telescopes (GSMTs). Yet despite its incredible achievements, AO still hasn’t fully succeded in bringing the quality of astronomical images to its full potential, required for modern observing techniques such as high-contrast imaging and/or coupling into single mode fibers, enabling the use of photonic technology.

Objectives of the PhD project

The next major breakthrough will come from using information of great value, available in the focal plane, to directly to drive AO systems. Such an approach is finally possible today, thanks to the availability of high-cadence, low readout noise near-infrared detectors and that of enhanced real time computing capabilities. Observatoire de la Côte d’Azur (OCA) and the Subaru Telescope are teaming up to offer a PhD project that will turn this ambitious goal into a reality. This PhD is funded by the KERNEL project. It will be co-supervised by the KERNEL project PI F. Martinache (OCA) and the Subaru Coronagraphic Extreme AO (SCExAO) project lead O. Guyon (Subaru Telescope).

The successful applicant will benefit from state of the art hardware and expertise along with access to two complementary experimental setups, both taking advantage of the same software environment:

  • the KERNEL test-bench, located in Nice (France), with a unique multi-wavelength capability, and a segmented deformable provides the means to prototype applications for GSMTs and long baseline interferometry developments.
  • the SCExAO instrument itself, installed at the Nasmyth focus of the Subaru Telescope, located atop Mauna Kea (Hawaii USA), provides the means to validate strategies using unique on-sky validation capability and have a rapid impact on the community.

Application process

The PhD should preferably start in the Fall 2018. To apply, the candidate is required to send (email a copy of his vita, and a letter detailing his/her interest in the project along with a transcript of his/her master degree in physics, astronomy or a relevant engineering specialty. The candidate should be willing to work as part of a team, to collaborate with an international network of people involved with a wide variety of activities: data processing, astrophysical modeling, observing at the telescope, experimentation in optics and real-time computing.

Habilitation à Diriger des Recherches

Dans le but de soutenir mon Habilitation à Diriger des Recherches (HDR), j’ai soumis à mes rapporteurs la première version de cette thèse, intitulée: “Repousser les limites de la diffraction pour l’astronomie à haute résolution angulaire”.

Page de garde de la HDR de Frantz

Deux versions de cette thèse sont téléchargeables ici au format PDF:

Si mes rapporteurs m’y autorisent, la soutenance de cette thèse de HDR devrait avoir lieu le jeudi 4 octobre 2018, à l’Observatoire de la Côte d’Azur, sur le site du Mont Gros.

Entrée de la Grande Coupole de l’Observatoire de la Côte d’Azur, sur la colline du Mont Gros, à Nice.

Pour les curieux, une page de Wikipedia explique ce qu’est la HDR et quel est le rôle de cette tradition qui ne semble exister qu’en Europe ainsi que dans quelques pays d’Afrique du Nord.

La thèse est évidemment écrite en LaTeX. Pour la mise en page, j’ai choisi d’utiliser la classe tufte-latex, inspirée par les publications de Edward Tufte. La lecture de son livre intitulé The Visual Display of Quantitative Information et de son essai intitulé Essay: The Cognitive Style of Powerpoint: Pitching Out Corrupts Within durant mon premier contrat de post-doctorat à l’Université de Cornell ont eu une forte influence sur ma méthode de communication scientifique: je les recommande tous les deux!

K-CAM: the KERNEL camera, is installed at the focus of SCExAO!

The Subaru Telescope at sunset

Toward the end of June 2018, the C-RED-1 camera built by First Light Imaging for the KERNEL project was installed on the Nasmyth IR focus of the Subaru Telescope and coupled with the SCExAO instrument.

Custom frame designed by Romain Laugier, KERNEL project PhD student and built by the OCA’s S2M service, to couple the C-RED-1 camera to the IR side port of SCExAO.

Frantz Martinache (KERNEL PI) reconnecting the KERNEL project C-RED-1 camera after installation of the camera on the IR side port of SCExAO.

Action shot of KERNEL PhD student Romain Laugier, fixing broken connections to the pulse-tube cooler of KCAM.

K-CAM: The KERNEL project C-RED-1 camera, is finally ready to observe on the IR side port of SCExAO.

Although it took more work than anticipated, the camera was successfully integrated to the SCExAO instrument both optically and in software, now using a VisioLink F4 frame grabber sold by EDT. The optics inside SCExAO make it possible to send light in focus to this camera and the images produced by the camera are written to shared memory so as to be integrated with the rest of the real time SCExAO software environment.

In its default full frame mode, the C-RED-1 makes it possible to acquire frames at 3.5 kHz. In its smallest window mode, the camera can run a little over 71 kHz. The high sensitivity of the camera, coupled with the high frame rate, are real game changers in the realm of high-contrast imaging and really make it possible to envision driving a deformable mirror directly from the focal plane. At these speeds, speckles don’t stand a chance!

The camera was partly commissioned on-sky during unfortunately rather poor observing conditions… but engineering observations are planned for October 2018 so this camera will get its chance to shine!

The software running the “K-cam” camera is maintained on Frantz’s github page.

Kernel-nulling talk in Grenoble

These are the slides of a presentation given on March 8, 2018 at IPAG, where I present research activities related to the KERNEL project, in particular the most recent development concerning the idea of kernel-nulling interferometry.

Predicted contrast detection limits for the L-band VIKiNG instrument concept proposed by Martinache & Ireland.

You can access the presentation file directly here.

Kernel-nulling for a robust direct interferometric detection of extrasolar planets

A new paper posted on arxiv by Frantz Martinache & Mike Ireland.


Combining the resolving power of long-baseline interferometry with the high-dynamic range capability of nulling still remains the only technique that can directly sense the presence of structures in the innermost regions of extrasolar planetary systems. Ultimately, the performance of any nuller architecture is constrained by the partial resolution of the on-axis star whose light it attempts to cancel out, and the design of nullers focuses on increasing the order of the extinction to reduce the sensitivity to this effect. However from the ground, the effective performance of nulling is dominated by residual time-varying instrumental phase errors that keep the instrument off the null. This is similar to what happens with high-contrast imaging, and is what we aim to ameliorate. We introduce a modified nuller architecture that enables the extraction of information that is robust against piston excursions. Our method generalizes the concept of kernel, now applied to the outputs of the modified nuller so as to make them robust to second order pupil phase error. We present the general method to determine these kernel-outputs and highlight the benefits of this novel approach. We present the properties of VIKiNG: the VLTI Infrared Kernel NullinG, an instrument concept within the Hi-5 framework for the 4-UT VLTI infrastructure that takes advantage of the proposed architecture, to produce three self-calibrating nulled outputs. Stabilized by a fringe-tracker that would bring piston-excursions down to 50 nm, this instrument would be able to directly detect more than a dozen extrasolar planets so-far detected by radial velocity only, as well as many hot transiting planets and a significant number of very young exoplanets.

December Stromlo KERNEL seminar

Presentation slides of a seminar given at Mt. Stromlo Observatory, in Canberra, Australia.

KERNEL: crack open the walnut
Slide extracted from a presentation introducing the the principles behind kernel-phase and KERNEL project. Click on image to download or access the presentation file!