The objective of this maturation project is to validate technologies for manufacturing infrared (IR) optics with gradient refractive index (GRIN) in two portable thermal imagers operating in the atmospheric window of 8-12 µm. One imager will be small field/long focal length for military application and the other will be large field/small focal length for civilian application (automotive for example). The feasibility of these technologies was demonstrated during the ASTRID "IRGRIN" project completed in June 2023 and the AID/DGA-Umicore thesis, defended in December 2022. This project clearly falls within the photonic thematic axis. The combination of the GRIN effect with the geometric power of curved surfaces offers exciting new possibilities for optical design. It is for example possible to design an optical system with a high focusing power, a large field of view and well corrected aberrations while having a low thickness, a low curvature and a reduced number of lenses compared to classic optical systems. Thus, the use of GRIN lenses would significantly reduce the size, weight and cost of optical systems, which is increasingly required for both military and civilian applications. During the initial project (ASTRID Project + DGA/AID Thesis), we demonstrated the feasibility of moldable IR GRIN optics with a diameter that can already reach 13 mm thanks to the development of an innovative and very fast ionic exchange process in optimized chalcogenide glasses. The perfectly reproducible profile presents a poly-nominal form of order 2. In addition, these optics present a negative constringency, which is rare and will make it possible to increase the aperture of the optic without degrading its performance. With these GRIN optics usable in the thermal infrared region between 3-5 or 8-12 µm, both military and civilian applications have been identified. In this maturation project, we plan to achieve a TRL≥5 for IR GRIN optics with negative constringency by achieving the following objectives: - Manufacture radial GRIN IR optics with an up-scalable process. - Manufacture spherical GRIN IR optics by molding axial GRIN glasses. - Develop an anti-reflective coating for IR GRIN optics. - Design, manufacture and qualify two prototype thermal imagers, the first with large field/short focal length using radial GRIN optic for civilian applications, the second with small field/long focal length using spherical GRIN for defense applications. These demonstrators will operate in the 8-12 µm spectral band. - Perform a market study and develop a valorization strategy. To achieve these ambitious objectives, the consortium is made up of three partners: an academic laboratory with thirty years of experience in infrared glasses, a public industrial laboratory which has long been developing expertise in optical instrumentation to anticipate future demand in optronic systems and a large multinational industrial group, world leader in infrared materials and optics. These partners have a long history of successful collaborations. The key issues for this technological maturation have been clearly identified. The solutions to address these issues, validated by extremely convincing results obtained during the initial project, are detailed.

The objective of this project is to develop infrared gradient refractive index (GRIN) optics based on chalcogenide glasses for thermal imaging in the 8-12 µm atmospheric window. A handheld infrared imaging demonstrator will be developed to evaluate the performance of these optics and two applications, a civilian one and a military one will be proposed. This project is clearly in the scope of "thématique 5 (photonique)" and especially "le sous-thème 6.5.3 (composants optiques : optiques moulables) of this call for projects. "Chalcogenides for glasses and fibers" are among the priorities of this theme. Combining the GRIN effect with the geometric power of curved surfaces offers exciting new possibilities for optical design. For example, it is possible to design an optical system with a high focusing power, a large field of view and well-corrected aberrations while having a small thickness, a small curvature and a reduced number of lenses compared to conventional optical systems. The high transparency of GRIN optics from the visible to thermal infrared would make it possible to combine several spectral bands. Thus, the use of GRIN lenses can significantly reduce the size, weight and cost of optical systems, which is increasingly required for both military and civil applications. Visible GRIN optics are generally fabricated through ion exchange in oxide glasses but right now, there is no GRIN optic that can be used in the thermal infrared range of 3-5 or 8-12 µm. In this project, we propose to develop moldable chalcogenide glass optics having gradient refractive index compatible with the targeted thermal imaging applications. The originality and the ambitious nature of this project are as follows: - Use of patented chalcogenide glasses for efficient ion exchange or controlled crystallization to obtain a refractive index gradient. - Development of a method for manufacturing GRIN IR optics by combining ion exchange and molding. - Development of a handheld LWIR prototype thermal camera to demonstrate the effectiveness of IR GRIN optics. To achieve the ambitious objectives, the consortium consists of three partners: an academic laboratory with thirty years of experience in infrared glasses, a public industrial laboratory that has long-term expertise in optical instrumentation to anticipate the evolution of future optronic systems and a leading multinational industrial group in infrared materials and optics. These partners have a long history of successful collaborations. Technological and scientific challenges are clearly identified. The solutions to address these challenges, validated by convincing preliminary results, are detailed in the proposal.

Additive manufacturing, or 3D printing, is proving to be a powerful development method in the field of materials science. Mainly used for polymers and plastics, additive manufacturing was extended to metals, to ceramics and, most recently, to glasses. Among all the families of glasses, the chalcogenide glasses known for their transparency in the mid-infrared range (between 0.5 µm and 20 µm, depending on their composition) exhibit a growing interest in scientific and industrial communities. Indeed, they could be used for numerous applications, such as thermal imaging and the generation of new sources of infrared light, as well as the needs of society in the fields of health and the environment with the development of infrared optical sensors. The MIR-3D project is at the crossroads between the emerging technologies of 3D printing in the field of glasses and the applications of chalcogenide glasses in the mid-infrared spectral window. In this context, the ambitious objective of the MIR-3D project is to develop an alternative shaping method for the elaboration of sensors, lenses, fibers and many other Mid-IR components. This approach is totally new and could allow less time-consuming synthesis, and less consummation of energy and raw material resources and consequently a reduction in manufacturing costs. This new manufacturing process is of particular interest to the three partner companies of the project: UMICORE IR glass for the production of MIR lenses, SelenOptics for the production of microstructured optical fibers and DIAFIR for the production of optical sensors. The project MIR-3D will be organized around 6 tasks: Task 0 : Coordination, communication and popular science Task 1 : Synthesis and 3D Printing of Chalcogenide Glasses Task 2 : Modeling of fiber and sensor structures Task 3: Elaboration of MIR lenses Task 4: Fabrication of hollow core fibers Task 5: Sensor Development and Spectroscopy The consortium of this project is constituted of 4 partners and 1 subcontractor, two academic laboratories : the Glasses and Ceramics team of the Institute of Chemical Sciences of Rennes, University of Rennes 1 (Elaboration of chalcogenide glasses, Study of 3D printing) and the Athena team of the Fresnel Institute of Aix-Marseille University (modeling of fibers and sensors), UMICORE IR glass (thermal camera lenses made of chalcogenide glass), SELENOPTICS (fiber optics made of chalcogenide glass) and DIAFIR (sensors made of chalcogenide glass, spectroscopy and medical diagnostics)

New strategic and growing markets related to connectivity, mobility, automotive, health and earth monitoring call for improved imaging solutions in visible, LWIR and VLWIR offering advanced functionalities and cost effectiveness. Visible imagers market is currently largely dominated by non-European countries. LWIR µbolometers imagers, fabricated above-IC, have not yet been democratized for high volume markets due to the difficulty to solve performance versus cost equation. However, Asian providers are making important progress to tackle this challenge. ATHENA aims at strengthening European economy in high-tech imaging technologies: - by taking advantage of 3D stacking technologies, improved sensor-processing integration, multimodal 2D/3D functionalities - by preparing the manufacturing of µbolometers from 200mm to 300mm CMOS wafers for productivity gain and access to more advanced CMOS nodes for improved functionalities, developing cost effective LWIR wafer level optic solutions - by using new methods of growing and doping materials for future VLWIR imager manufacturability. This will foster new applications related to automated systems (in industry, border and security management), health and consumer markets, and earth & climate monitoring. ATHENA gathers a strong European consortium composed of highly renowned Research Technological Organizations, big industrial players in imaging technologies and end-users to specify, design, develop, test these technologies in use cases and set common specifications for the imagers to support their industrialization and widespread adoption. In line with both the European Union’s Chips Act and the Electronics, Components and Systems Strategic Research and Innovation Agenda, ATHENA will not only address the development of new sensors and chips, but also their integration in larger systems to pave the way to promising applications. ATHENA will strongly contribute to Europe leadership, industrial competitiveness and sovereignty.