Publications by authors named "K Belkebir"

Biomedical imaging lacks label-free microscopy techniques able to reconstruct the contour of biological cells in solution, in 3D and with high resolution, as required for the fast diagnosis of numerous diseases. Inspired by computational optical coherence tomography techniques, we present a tomographic diffractive microscope in reflection geometry used as a synthetic confocal microscope, compatible with this goal and validated with the 3D reconstruction of a human effector T lymphocyte.

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Estimating three-dimensional complex permittivity of a sample from the intensity recorded at the image plane of a microscope for various angles of illumination, as in optical Fourier ptychography microscopy, permits one to avoid the interferometric measurements of classical tomographic diffraction microscopes (TDMs). In this work, we present a general inversion scheme for processing intensities that can be applied to any microscope configuration (transmission or reflection, low or high numerical aperture), scattering regime (single or multiple scattering), or sample-holder geometries (with or without substrate). The inversion procedure is tested on a wide variety of synthetic experiments, and the reconstructions are compared to that of TDMs.

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The standard two-dimensional (2D) image recorded in bright-field fluorescence microscopy is rigorously modeled by a convolution process involving a three-dimensional (3D) sample and a 3D point spread function. We show on synthetic and experimental data that deconvolving the 2D image using the appropriate 3D point spread function reduces the contribution of the out-of-focus fluorescence, resulting in a better image contrast and resolution. This approach is particularly interesting for superresolution speckle microscopy, in which the resolution gain stems directly from the efficiency of the deconvolution of each speckle image.

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We present a theoretical and numerical study of coherent anti-Stokes Raman scattering Fourier ptychography microscopy (CARS-FPM), a scheme that has not been considered so far in the previously reported CARS wide-field imaging schemes. In this approach, the distribution of the Raman scatterer density of the sample is reconstructed numerically from CARS images obtained under various angles of incidences of the pump or Stokes beam. Our inversion procedure is based on an accurate vectorial model linking the CARS image to the sample and yields both the real and imaginary parts of the susceptibility, the latter giving access to the Raman information, with an improved resolution.

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