ULTRA-LIGHT, SELF-CORRECTING, “LIVE” MIRRORS: Lowering the areal density of mirrors and maximizing performance with non-abrasive, additive, 3D-printed novel technology.

Project Information

Live-Mirror

Grant agreement ID: 101099220

DOI

10.3030/101099220

EC signature date 11 January 2023

Start date 1 February 2023

End date 31 January 2028

Funded under

• The European Innovation Council (EIC)

Total cost

€ 3 334 517,50

EU contribution

€ 3 334 517,50

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 2 - Live-Mirror (ULTRA-LIGHT, SELF-CORRECTING, “LIVE” MIRRORS: Lowering the areal density of mirrors and maximizing performance with non-abrasive, additive, 3D-printed novel technology.)

Reporting period: 2024-02-01 to 2025-07-31

Summary of the context and overall objectives of the project

We propose to develop ultralight, self-correcting mirrors for the next generation of large optical telescopes and solar energy concentrators. Presently, the best mirrors have a density of about one-half a metric ton per square meter or more to provide the stiffness which is necessary to keep the optical shape under the variable conditions given by the changing gravity vector as the telescopes track a position on the sky, as well as to withstand variable wind conditions. We intend to replace such a massive mirror with a “sandwich” of very light, optically perfect, “fire-polished glass” sheets stiffened with layers of Electro-active polymers (EAP) that can be deposited through additive manufacturing 3D printers. The sheets of glass slumped in a pressurized, tailored kiln and allowed to relax onto a suitable mould, cast to a predetermined off-axis aspheric shape while keeping the excellent optical surface quality of fire-polished glass. Using the addressable energy of the EAP will provide dynamically self-controlled stiffness and variable push-pull action real-time multi-sensing controlled and calibrated to keep the optical surface to a “live-perfect” shape under general operating conditions. These “Live-Mirrors” shall provide optical surfaces of as high a quality as those of the current best telescopes but with more extensive dynamic range and a reduction in weight and cost of more than one order of magnitude. Such mirrors will allow the development of large class telescopes (see Figure 1) and the next generation of space telescopes. On the ground, they will also offer very low-cost options for the next generation of solar energy concentrators and antennas for optical communication. (see above Figure 2).

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Live-Mirror is based on three main objectives, delivering three state-of-the-art breakthrough technologies:

(1) First we will demonstrate that an accurate on-/off-axis aspheric surface can be generated without ever contacting the glass's reflecting surface, e.g. a zero-polishing mirror. We aim to create the initial aspherical optics without grinding or melting the reflective surface and to do it inexpensively. The science-towards technology breakthroughs of these processes will produce a several-meter-scale aspherical (parabolic) thin (from 3-to-6mm) fire-polished lightweight surface with exceptional control of the level of diffusely scattered light, e.g. improved high-dynamic range, which will be superior to conventionally ground mirrors (10x less scattered light);

(2) Second, the research objective will be focused on modelling and creating in the lab a dynamic hybrid meta-materials structure (HM-MS) by the sandwiching of warpable thin-glass control (fire-polished) and reaction surfaces (see Figure 3), separated by a deterministically distributed lattice of EAP-based force actuators in series with force sensors interconnected by flexible electronics via additive manufacturing. Why additive manufacturing? -- Because each m2 of optical mirror area will require about 100s of force points, additive manufacturing via 3D printing technologies is crucial to enabling this degree of complexity and miniaturization. We will investigate a range of static and dynamic limits for a given areal mass density and useful surface shapes;

(3) Third objective calls for novel, fast & unique multi-frequency metrology & control, which will be crucial to assess the performance, calibration and control for the Live-Mirror overall HM-MS system in close-loop & real-time. In addition, unique multi-sensing performance, calibration and metrology algorithms integrated into a control system will shape our HM-MS dynamically (real-time) into a perfect optical surface by including the feedback of measurement of the wavefront in a closed loop, delivering performance with nanometric precision.

Within this project, we will tackle some of the most challenging issues that will be simulated, modelled and validated on a laboratory ½ meter-class HM-MS "workhorse" demonstrator – hundreds of force-actuators & -sensors interconnected via flexible electronics, as it is starting to show up with our first proof-of-concept.

The consortium’s work is synergistically distributed among six European partners inside the consortium and is closely related to the R&D of newly derived sub-technologies for the leading Live-Mirror technology.
In this first year of Y1 activities, each of the three main objectives, as distributed and shown in Figure 4, had started to consolidate their contributions R&Ds on mould, slumped glass, glass coating, ink and EAP, 3DPrinter, metrology and electronics control –– towards the main objective: the proofs-of-concept for the Live-Mirror dynamic hybrid meta-materials structure (HM-MS). Figure 5 shows one of these “freshly baked” proofs-of-concept direct from the EIC Live-Mirror version_01 for the additive manufacturing facility.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The EIC Live-Mirror consortium is strongly committed to advancing the state of the art in producing accurate mirrors. Our proposed lightweight, diffraction-limited, meta-material-based optical system technology targets the following breakthroughs: lower areal mass density of mirrors (x7), lower surface roughness and scattered light (x10), and faster and lower cost production (x15). Our strategy is to assess and comply with the needs of ground and space astronomy and astrophysics (A&A) applications. The specifications for A&A optical mirrors are the most challenging: extremely lightweight, very precise shape, and high surface quality, enabling very low light scattering. Requirements for space observation and exploration are highly demanding and have always led to the development of breakthrough technologies whose impact on the economy and society has yet to be foreseen. Two significant spin-offs from astronomy are (1) the CCD devices through the developments forced by their use in sensitive astronomical observations that the modern, low-noise, megapixel versions were developed; and (2) the Wi-Fi technology protocols.

Our Live-Mirror technology prototype should be scalable, allowing us to create large and very precise optical surfaces and deliver the next generation of extremely lightweight Earth-, space-, or Moon-based telescopes. In addition, this technology will serve all applications requiring precise and cheap remote detection, such as (i) Astronomical systems, (ii) Wireless optical communication systems (UV and free-space systems), (iii) Light-collection systems for the production of clean, solar energy plants; (iv) Space surveillance (of both Earth and near-Earth environments), for public security and resources.

Visionary technologies (see Figure 2)

Live-Mirror the three main objectives, as distributed and shown in Figure 4

the proofs-of-concept for the Live-Mirror dynamic hybrid meta-materials structure (HM-MS)

Live- mirrors will allow the development of 50-100 meter-class telescopes (see Figure 1)

(HM-MS) Reaction Surfaces (see Figure 3)