In the context of multi-wavelength in-line holographic microscopy of micrometer-sized samples, we propose a 2-step methodology to estimate geometric and chromatic aberrations of the optical system and then use this calibration step to better reconstruct the complex transmittance at focus. The first step uses an aberration-wise Lorenz-Mie model to jointly estimate the parameters of calibration beads spread in the sample and 14 Zernike coefficients at each wavelength. Then, the reconstruction step is performed using a regularized inverse problems approach reconstruction of the whole multi-wavelength data set with a colocalization hypothesis. This general methodology is applied to the case of Gram-stained bacteria on blood smears. On these samples, in addition to providing a new information (phase), we show interesting improvements on the image quality, which promises better discrimination between bacteria types and enhanced repeatability.
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