ATICS

Digital Inline Holography (DIH) is a fast-developing 3D coherent imaging technique. With a single, compact and low-cost optical set-up, it has the potential to provide, with an unsurpassed large depth of field and multi-scale capabilities, detailed information on complex shape and low contrast micro- to milli- meter objects encountered in many scientific, industrial and health areas. ATICS (Advanced Three-dimensional Imaging of Complex particulate Systems) is a four-year research and collaborative project carried out by four university, CNRS, engineer schools and CEA laboratories. Its main objective is to develop a set of advanced and robust light scattering and reconstruction tools and methods, than can increase tenfold the practical capabilities of DIH. All for the purpose of in-situ characterization of the 3D dynamics, shape, size and composition of particulate and biological media encountered in, today’s research of primary societal importance, and most notably for recycling, materials processing, biological imaging and ultrasound therapies. Based on the partners complementary expertise, all scientific aspects of the problem are fully addressed in this project. First, it is necessary to improve the modelling of the hologram formation, propagation, and recording (electromagnetic simulations and asymptotic light scattering models). A next step is to better account for issues raised by hologram magnification (with camera lenses, microscopes objectives, as well as converging and diverging illumination beams) and optical aberrations introduced by optics and interfaces. Another issue is to account for more realistic object shapes and properties (distorted droplets, particle aggregates, details of bacterial morphology…). The development of advanced reconstruction methods, based on back propagation and inverse problems approaches, is certainly a major contribution of the ATICS project. These new methods are to be implemented into fast parallel computing and machine learning algorithms to solve the time-consuming issue and provide efficient tools for applications. The applicability of these tools is demonstrated via four experiments in different up to date research areas: (i) cold sprays, with surface deposition issues on thermosensitive support; (ii) bubbly flow interacting with an acoustic field, for innovative ultrasound therapies; (iii) reactive droplets in milli- and micro-fluidic flows and in levitation, with liquid-liquid transfer and recycling issues; (iv) living micro-organisms, with detection issues in various biological fluid samples. These four applications are also designed to bring physical insight and validation data for the modelling aspects as well as to increase the impact and benefits of the project for the scientific and industrial communities involved. Dissemination of knowledge and transfer is also an important part of the ATICS project, with notably the training of 9 Master of Sciences and 2 PhD students, and 1 postdoctoral researcher. Special attention is also paid to the publication and communication of scientific results in high-level journals, national and international conferences, as well as the organization of a thematic day, a conference, the sharing of digital tools on a GitHub repository and, as part of the open science movement, publications in media with a large audience (Wikipedia articles).