Frédéric Diaz

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We consider optimization of hybrid imaging systems including a phase mask for enhancing the depth of field and a digital deconvolution step. We propose an image quality criterion that takes into account the variability of the system's point-spread function along the expected defocus range and the noise enhancement induced by deconvolution. Considering the(More)
In the paraxial Debye regime, simple and power-efficient pupil filters are designed to break the diffraction limit along a large depth of focus (DOF) for the Gaussian beam. Dependences of the superresolution factor, DOF gain, Strehl ratio, sidelobe strength, and axial intensity nonuniformity on the Gaussian profile in the pupil plane are characterized using(More)
Different methods such as axilens and binary-phase filter have been investigated to improve the depth of focus. A method is proposed to calculate an amplitude-phase pupil filter and obtain the desired distribution of intensity along the optical axis. It produces a narrow spot with a uniform intensity level over a large depth of focus, comparable to the(More)
The vulnerability of human populations and natural systems and their ability to adapt to extreme events and climate change vary with geographic regions and populations. Regional climate models (RCM), composed by an atmospheric component coupled to a land surface scheme and driven over ocean areas by prescribed sea surface temperature, have been developed to(More)
A mechanistic physiological model of the appendicularian Oikopleura dioica has been built to represent its three feeding processes (filtration, ingestion and assimilation). The mathematical formulation of these processes is based on laboratory observations from the literature, and tests different hypotheses. This model accounts for house formation dynamics,(More)
We consider optimization of hybrid imaging systems including a pupil mask for enhancing the depth of field and a digital deconvolution step. In a previous paper [Opt. Lett. 34, 2970 (2009)] we proposed an optimization criterion based on the signal-to-noise ratio of the restored image. We use this criterion in order to optimize different families of phase or(More)
In a classical imaging system, the object is imaged on a sensor by an optical system which should provide an image as good as possible. A post processing step can then be implemented, but the optimization of the optics and the post processing is done separately. In an hybrid imaging system, the optimization of the optics and the post-processing step is(More)
Imaging systems that combine a phase mask in the pupil and digital postprocessing may have better performance than conventional ones. We have built such a system to enhance the depth of field of an uncooled thermal camera. The phase masks are binary, their structures are optimized thanks to an image quality criterion, and they have been realized with three(More)
To improve the depth of field in imaging systems, we propose a new method for designing pupil filters with the classical approach used for computer-generated holograms. This method allows us to calculate a complex amplitude/phase filter in order to obtain a desired distribution of intensity along the optical axis, and thus the desired depth of field. We(More)
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