Interview – Laboratoire d’Astrophysique de Marseille (LAM)
Interview – Laboratoire d’Astrophysique de Marseille (LAM)

1. Can you introduce yourself and your organization?

My name is Benoit Neichel, and I have been a researcher at the Laboratoire d’Astrophysique de Marseille (LAM) for about 10 years. Our laboratory is affiliated with the CNRS and Aix Marseille University. My research focuses on instrumentation for large telescopes in astronomy, particularly in the field of Adaptive Optics (AO).

Within the laboratory, there are several scientific groups: one dedicated to galaxy evolution, another focused on exoplanets and objects within the solar system, and finally, the one I work with as the head of research and development in instrumentation. Our goal is to design and develop innovative instrumentation for large ground-based telescopes, including developments in AO.

2. In what context do you use Adaptive Optics and Deformable Mirrors?

Adaptive Optics in astronomy is used to correct the effects of atmospheric turbulence and restore image quality at the focal plane of large telescopes. These increasingly large telescopes are designed to collect more light to observe objects such as distant galaxies and exoplanets. These telescopes are seen as true photon funnels. A larger telescope also allows for more details in the images; the larger the telescope, the better the discernment of details and the better the understanding of the observed objects. However, this improvement is only possible if the telescope is placed in space, without atmospheric disturbances.

For ground-based telescopes observing through the Earth’s atmosphere, images are degraded and blurred due to atmospheric turbulence. With this disturbance, we won’t see more details with an 8-meter telescope than with a 10 or 20-centimeter telescope.

Thus, without OA, we lose all the capacity of the power of large telescopes; Adaptive Optics allows us to correct the optical aberrations created by atmospheric turbulence, sometimes quite strong. Adaptive Optics systems, such as deformable mirrors and wavefront sensors proposed by ALPAO, will then allow us to measure and correct deformations in real-time to restore image quality.

Currently, our largest telescopes reach 8-10 meters in diameter, but we are investing in the construction of a very large telescope with a diameter of 39 meters, the European Extremely Large Telescope (ELT) in Chile. This telescope will operate exclusively with Adaptive Optics, requiring the most advanced technologies to measure and correct optical aberrations and restore images at the diffraction limit.

3. What perspectives do you foresee for AO in astronomy?

Regarding Adaptive Optics (AO) in astronomy, we envision several promising perspectives. Firstly, in our constant pursuit of performance enhancement, we seek to push technologies further, particularly by collaborating with industrial partners such as ALPAO. One key aspect of AO performance, exemplified by mirrors, lies in the number of actuators and therefore in the number of correction points. With increasingly large telescopes, such as those reaching forty meters in diameter, we require mirrors with a growing number of actuators to significantly improve image quality. This technological challenge will be necessary from companies like ALPAO.

Secondly, it is crucial for mirrors to react swiftly, as optical aberrations induced by atmospheric turbulence evolve rapidly. To achieve the best performance and image quality possible, we are thus aiming to accelerate the aberration correction process.

And as we always want everything simultaneously, we are working in collaboration with partners like ALPAO to identify critical mirror parameters and improve their design. We are also assessing the impacts of these improvements on astronomical observations to optimize the entire process and make the most of future very large telescopes.

Another essential aspect to mention that drives us towards technology development is the study of exoplanets. Exoplanets are planets orbiting stars much like Earth orbits the Sun, forming planetary systems. This is a major focus of the European Extremely Large Telescope: characterizing exoplanets and their atmospheres and determining if there are other planets with Earth-like characteristics.

Characterizing these exoplanets requires XXL AO systems to correct aberrations and obtain precise images, due to the weakness of the signal to detect. The ultimate goal is to analyze the light from these planets with spectrographs to identify potential biological markers, such as the presence of water, CO2, oxygen, or molecules indicative of life. This quest, as complex as it is fascinating, could provide crucial insights into the processes of life development.

That’s why the technologies offered by ALPAO are indispensable to us: nothing would be possible without AO and deformable mirrors in our telescopes.

4. How long have you been working with ALPAO products?

It’s been quite some time. I’ve been working with various ALPAO products, including deformable mirrors and developments related to real-time computer (RTC). This collaboration dates back several years. In fact, I met Julien Charton a long time ago when he was an engineer at LAOG, now IPAG, where he was beginning to develop the coil technology that is now the building block of ALPAO mirror actuators. At that time, I was still an intern, so I’ve known him for quite a while.

In recent years, we have intensified our collaborations. Over the past 4-5 years, we have engaged in numerous joint projects between the Laboratoire d’Astrophysique de Marseille and ALPAO. For example, we currently have an ongoing thesis with a PhD student shared between our two entities. Prior to that, as part of the post-COVID recovery plan, we also shared an engineer between ALPAO and our laboratory. Additionally, we are collaborating on a project to build a new Adaptive Optics system for the Gemini North telescope (GNAO) in the United States. This collaboration continues to deepen and greatly benefits both of our entities.

5. What advantages do you see in our deformable mirrors, in our technology?

In the market for deformable mirrors, there isn’t an infinite array of products and options.

Generally, we turn to ALPAO products for intermediate-sized mirrors. For very large mirrors (Adaptive Secondary Mirrors, ASM), which sometimes require significant modifications to telescope optics, we rely on specific technology developed by other manufacturers. Similarly, for very small deformable mirrors, we explore other technological solutions.

However, for intermediate diameters in terms of pupil size, ALPAO products perfectly meet our specifications and needs in terms of actuators, speed, and functionality. Additionally, they are robust and reliable.

The scientific links and collaborations between our laboratories and ALPAO are immensely helpful; this allows us to precisely express our needs and thus benefit from products that exactly meet our expectations. It also helps us make well-informed decisions in selecting our products and benefit from specific scientific and technical support; it’s more than just after-sales service!

The astronomical community isn’t massive; we don’t purchase hundreds of deformable mirrors. That’s why having a partner like ALPAO who understands and supports our needs is crucial for us.

6. Would you recommend ALPAO to your community?

Absolutely. We are very satisfied with ALPAO mirrors.

Additionally, we have established a shared AO bench, Papyrus. Located at the Observatoire de Haute-Provence (OHP), this bench allows us to test components and technologies as well as deformable mirrors, wavefront analyzers, and the real-time controller developed internally.

All of these projects are part of our collaboration that I mentioned earlier and which is working very well, so I wouldn’t hesitate to recommend ALPAO products to our community!

7. Can you tell me about your professional experience in Chile? What are your memories?

Before joining the Laboratoire d’Astrophysique de Marseille, I spent five years at the Gemini Observatory in Chile, halfway between Santiago and the Atacama Desert. It is located a few hundred kilometers south of the well-known VLT telescopes, familiar to Europeans.

During my time there, I worked on implementing a rather unique Adaptive Optics system. It was the first time we used multiple laser stars. In Adaptive Optics, it’s essential to measure deformations caused by atmospheric turbulence to correct them using deformable mirrors. To do this, we can project lasers into the sky and use the light from these artificial stars that we create.

Thus, in Chile, we developed the first AO system using multiple laser stars. Instead of firing a single laser, we fired 5 and thus created an artificial constellation. This allowed us to measure and correct turbulence over a much larger field than before.

This experience was extremely enriching: it was a first! We learned a lot about how these new systems operate, their interaction with telescopes, and the scientific advances we were able to achieve with them. This experience was great because our new system allowed us to make unprecedented astronomical and astrophysical discoveries. Ultimately, that was our greatest reward.

8. What results do you expect from the GNAO project and how will AO contribute to it?

GNAO is a project aimed at implementing an Adaptive Optics (AO) system for the Gemini North telescope, located in Hawaii. The two twin telescopes, one in the Southern Hemisphere (Chile) and the other in the Northern Hemisphere, provide complete sky coverage in their observations.

The goal of the GNAO project is to develop a new AO system based on the technology with multiple laser stars that I described earlier. This system will be associated with the GIRMOS instrument, which allows spectroscopy of distant galaxies. It will correct atmospheric turbulence, thus providing better concentration of light from distant galaxies and thereby understanding the processes of galaxy formation and evolution.

In reality, like stars and the universe, galaxies have a life cycle; they are born and evolve over time through processes such as galaxy mergers or gas accretion. These evolutions stimulate star-forming regions within these galaxies, potentially forming planets capable of supporting life (like planet Earth). However, these processes of galaxy formation and evolution are not yet fully understood. The challenge lies in observing these large samples of galaxies to better understand their evolution and reconstruct their history. In astronomy, our information relies primarily on observation: we cannot put a galaxy in a laboratory! That’s why telescopes and AO are indispensable tools for obtaining information. The future GNAO instrument, equipped with this spectrograph, will then probe these samples of galaxies and provide clues and theories about all the processes of galaxy formation. This is the main scientific objective.

There are also other scientific applications, such as understanding star clusters, studying star formation in our galaxy and neighboring galaxies. Is the process universal? How does it evolve? All of this is made possible by AO, which offers better angular resolution and thus facilitates the understanding of all these processes.


Benoit Neichel is a CNRS researcher at the Laboratoire d’Astrophysique de Marseille where he leads the research and development group. He obtained his doctorate in 2008, conducting integral field spectroscopy observations of distant galaxies using Wide Field Adaptive Optics. He then worked at the Gemini South Telescope for nearly five years as the scientific lead for the GeMS instrument. In 2013, he joined LAM, and he is currently involved in preparing for the future Extremely Large Telescope, serving as the deputy-PI for the HARMONI project.