Context and problematics:
Optical microscopy techniques are among the preferred methods for biological studies, thanks to their unique capability of imaging living specimens in 3-D. Tomographic diffractive microscopy (TDM) is a new technique, which permits to image transparent specimens in 3-D , without preparation or staining. It combines micro-holography with tomographic acquisitions, performed by either specimen rotation or illumination scanning. It allows for the measurement of the specimen index of refraction distribution in 3-D, and with a resolution twice better than conventional microscopy.
IRIMAS has built such a microscope [2,3], which has demonstrated its ability to reach an isotropic 3-D resolution in the 100 nm range .
The HORUS project, involving a collaboration between the IRIMAS laboratory (Mulhouse), the Hubert Curien laboratory (Saint-Étienne) and the IGBMC institute (Strasbourg), and funded by the Agence Nationale de la Recherche (ANR), aims at improving this imaging technique in terms of instrumentation and image processing for reconstruction. The goal is to adapt the technique to the imaging of living samples.
Subject of the Post-Doc:
The Post-Doc is inserted in the improving task of 3D reconstruction algorithms, which is an active research area. The recruited candidate will have to improve or overcome already existing reconstruction methods, mostly based on the direct inversion of first Born approximation [5,2,6]. The HORUS project particularely aims at exploring inverse problems approaches to perform the reconstruction [7,8,9,10,11], with the ambitious challenge of reaching high spatial and temporal resolution to make possible to image microscopic living samples. In this context, one of the main concerns is the numerical modelization of the image formation process, which deals with 3D diffraction physics [12,13,14,6], which is a correlated task of the HORUS project.
High interactions and transfers of knowledge will occur with the IRIMAS laboratory. A PhD thesis at IRIMAS, mixing instrumentation and image processing (subject available on the web site of the GdR ISIS: http://www.gdr-isis.fr/news/5657/121/High-Resolution-Tomographic-Diffractive-Microscopy-Instrumentation-and-Image-processing.html), will also start soon, and will be highy interconnected with this Post-Doc.
Required skills: signal and image processing, physical optics (interferometry, diffraction). An experience in image reconstruction (digital holography, tomography) and/or inverse problems (modelization, regularization, numerical optimization) would be a valuable additional asset.
 O. Haeberlé, K. Belkebir, H. Giovaninni, and A. Sentenac. Tomographic diffractive microscopy: basics, techniques and perspectives. Journal of Modern Optics, 57(9):686–699, May 2010.
 Matthieu Debailleul, Bertrand Simon, Vincent Georges, Olivier Haeberlé, and Vincent Lauer. Holographic microscopy and diffractive microtomography of transparent samples. Measurement Science and Technology, 19(7):074009, 2008.
 B. Simon, M. Debailleul, V. Georges, V. Lauer, and O. Haeberlé. Tomographic diffractive microscopy of transparent samples. The European Physical Journal - Applied Physics, 44(1):29–35, October 2008.
 Bertrand Simon, Matthieu Debailleul, Mounir Houkal, Carole Ecoffet, Jonathan Bailleul, Joël Lambert, Arnaud Spangenberg, Hui Liu, Olivier Soppera, and Olivier Haeberlé. Tomographic diffractive microscopy with isotropic resolution. Optica, 4(4):460–463, April 2017.
 Emil Wolf. Three-dimensional structure determination of semi-transparent objects from holographic data. Optics Communications, 1(4):153–156, September 1969.
 J. Bailleul, B. Simon, M. Debailleul, L. Foucault, N. Verrier, and O. Haeberlé. Tomographic diffractive microscopy: Towards high-resolution 3-D real-time data acquisition, image reconstruction and display of unlabeled samples. Optics Communications, 422:28–37, September 2018.
 Yongjin Sung, Wonshik Choi, Christopher Fang-Yen, Kamran Badizadegan, Ramachandra R. Dasari, and Michael S. Feld. Optical diffraction tomography for high resolution live cell imaging. Optics Express, 17(1):266, January 2009.
 Micah H. Jenkins and Thomas K. Gaylord. Three-dimensional quantitative phase imaging via tomographic deconvolution phase microscopy. Applied Optics, 54(31):9213–9227, November 2015.
 Anthony Berdeu, Fabien Momey, Bastien Laperrousaz, Thomas Bordy, Xavier Gidrol, Jean-Marc Dinten, Nathalie Picollet-D’hahan, and Cédric Allier. Comparative study of fully three-dimensional reconstruction algorithms for lens-free microscopy. Applied Optics, 56(13):3939–3951, May 2017.
 H. Y. Liu, U. S. Kamilov, D. Liu, H. Mansour, and P. T. Boufounos. Compressive imaging with iterative forward models. In 2017 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pages 6025–6029, March 2017.
 Thanh-An Pham, Emmanuel Soubies, Alexandre Goy, Joowon Lim, Ferréol Soulez, Demetri Psaltis, and Michael Unser. Versatile reconstruction framework for diffraction tomography with intensity measurements and multiple scattering. Optics Express, 26(3):2749–2763, February 2018.
 U. S. Kamilov, I. N. Papadopoulos, M. H. Shoreh, A. Goy, C. Vonesch, M. Unser, and D. Psaltis. Optical Tomographic Image Reconstruction Based on Beam Propagation and Sparse Regularization. IEEE Transactions on Computational Imaging, 2(1):59–70, March 2016.
 Emmanuel Soubies, Thanh-An Pham, and Michael Unser. Efficient inversion of multiple-scattering model for optical diffraction tomography. Optics Express, 25(18):21786–21800, September 2017.
 H. Y. Liu, D. Liu, H. Mansour, P. T. Boufounos, L. Waller, and U. S. Kamilov. SEAGLE: Sparsity-Driven Image Reconstruction under Multiple Scattering. IEEE Transactions on Computational Imaging, PP(99):1–1, 2017.