Conference Agenda

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We present a fully quantitative full-field optical coherence tomography realized in transmission. This method allows, for the first time, a direct and fast retrieval of the complex amplitude of light that propagated through the sample of interest. We show that with an appropriate spectral range of the swept-source laser, this method separates weakly-scattered photons from the multiply-scattered ones, thus allowing measurement of thick and scattering samples, like tissue slices or organoids. With a relatively easy optical setup and straightforward numerical processing, this method is superior to classical quantitative phase imaging methods like digital holographic microscopy.

Interferometers for displacement measurement with picometer resolution are required. The main cause of degradation of interferometer resolution is air fluctuation. To investigate the effect of air fluctuation on displacement resolution, we have developed a sinusoidal phase modulation interferometer capable of measuring 1D displacement with 10 picometer resolution and 2D in-plane displacement (air fluctuation). The interferometer is of Michelson type with different polarizations in the reference and measurement arms. By exchanging the phase-modulated electro-optical modulator and photodetector of this interferometer, 1D and 2D in-plane displacements can be measured, respectively.

We propose a maximum-likelihood estimation (MLE) framework tailored to event-driven detectors, such as Timepix3, to perform computational image reconstruction from event trigger data. Unlike frame-based acquisitions, which aggregate intensities over an exposure period, event-driven cameras asynchronously record time-of-arrival data whenever a pixel exceeds a photon-count threshold. Our approach models the Poissonian probability of photon arrivals and incorporates both triggered (event) and untriggered (non-event) pixels into a unified log-likelihood function that remains well-defined across low-dose and saturation regimes. This naturally addresses challenges such as imaging under scarce photon conditions and pixel saturation in a consistent manner. Using gradient-based optimization, this MLE framework can be applied to several computational imaging techniques such as ptychography or coherent diffraction imaging.

Iterative reconstruction algorithms are commonly employed in in-line digital holography to retrieve phase information from one or more intensity images. The methods rely on iterative propagation of the complex wavefront between the measurement and reconstruction planes. To address the ill-posed nature of the reconstruction problem, constraints are applied in each plane. Despite yielding quantitative phase information, these approaches ignore aberrations introduced by the optical system. We propose a straightforward extension to these iterative algorithms to account for these aberrations, modelled here as a complex point spread function (PSF). Because the PSF can vary across the field of view, two scenarios have been investigated: one accounting for PSF variation and one ignoring it. With equal computational cost for convolution, and hence reconstruction time, the proposed method improves the accuracy of aberrated holograms reconstructions.