Trade-off asymmetric profile for extended-depth-of-focus ocular lens

We explore the possibility of extending the depth of focus of an imaging lens with anasymmetric quartic phase-mask, while keeping the aberration within a relatively low level. Thiscan be intended, for instance, for ophthalmic applications, where no further digital processingcan take place, relying instead on the patient’s neural adaptation to their own aberrations. Wepropose a computational optimization method to derive the design-strength factor of the asymmetricprofile. The numerical and experimental results are shown. The optical experiment was conductedby means of a modulo-2pphase-only spatial light modulator. The proposed combination of theasymmetric mask and the lens can be implemented in a single refractive element. An exemplarycase of an extended-depth-of focus intraocular lens based on the proposed element is described anddemonstrated with a numerical experiment.Funding for this project was provided by the following: Agencia Estatal de Investigación (Spanish government) and European social fund, (PID2020-114582RB-I00/AEI/10.13039/501100011033); Centre de Cooperació i Desenvolupament, Universitat Politècnica de Catalunya-BarcelonaTech (Spain), Project B004-2019; Ministerio de Ciencia, Tecnología e Innovación (Colombia), Project 124489786239 (Contract 763-2021).Peer ReviewedPostprint (published version

Lente programable multifocal: Combinación coaxial y multieje

Postprint (published version

Detection and removal of dust artifacts in retinal images via sparse-based inpainting

Dust particle artifacts are present in all imaging modalities but have more adverse consequences in medical images like retinal images. They could be mistaken as small lesions, such as microaneurysms. We propose a method for detecting and accurately segmenting dust artifacts in retinal images based on multi-scale template-matching on several input images and an iterative segmentation via an inpainting approach. The inpainting is done through dictionary learning and sparse-based representation. The artifact segmentation is refined by comparing the original image to the initial restoration. On average, 90% of the dust artifacts were detected in the test images, with state-of-theart restoration results. All detected artifacts were accurately segmented and removed. Even the most challenging artifacts located on top of blood vessels were removed. Thus, ensuring the continuity of the retinal structures. The proposed method successfully detects and removes dust artifacts in retinal images, which could be used to avoid false-positive lesion detections or as an image quality criterion. An implementation of the proposed algorithm can be accessed and executed through a Code Ocean compute capsule.The authors acknowledge the financial support from the Centre de Cooperació i Desenvolupament (CCD) at the Universitat Politècnica de Catalunya under project ref. CCD 2019-B004, and from the Universidad Tecnológica de Bolívar. Authors are grateful to Juan Luís Fuentes from the Miguel Servet University Hospital (Zaragoza, Spain) for providing the real images from clinical practice. E. Barrios thanks Minciencias and Sistema General de Regalías (Programa de Becas de Excelencia) for a PhD scholarship. E. Sierra thanks the Universidad Tecnológica de Bolívar for a post-graduate scholarship. Parts of this work were presented at the Pattern Recognition and Tracking XXX - SPIE DCS, 2019 [39]. L. Romero, A. Marrugo, and M.S. Millán thank the funds provided by the Spanish Ministerio de Ciencia e Innovación under the project reference PID2020-114582RB-I00.Peer ReviewedPostprint (published version

Corneal endothelium assessment in specular microscopy images with Fuchs’ dystrophy via deep regression of signed distance maps

Specular microscopy assessment of the human corneal endothelium (CE) in Fuchs’ dystrophy is challenging due to the presence of dark image regions called guttae. This paper proposes a UNet-based segmentation approach that requires minimal post-processing and achieves reliable CE morphometric assessment and guttae identification across all degrees of Fuchs’ dystrophy. We cast the segmentation problem as a regression task of the cell and gutta signed distance maps instead of a pixel-level classification task as typically done with UNets. Compared to the conventional UNet classification approach, the distance-map regression approach converges faster in clinically relevant parameters. It also produces morphometric parameters that agree with the manually-segmented ground-truth data, namely the average cell density difference of -41.9 cells/mm2 (95% confidence interval (CI) [-306.2, 222.5]) and the average difference of mean cell area of 14.8 µm 2 (95% CI [-41.9, 71.5]). These results suggest a promising alternative for CE assessment.This work has been partly funded by Ministerio de Ciencia, Tecnología e Innovación, Colombia, Project 124489786239 (Contract 763-2021), Universidad Tecnológica de Bolívar (UTB) Project CI2021P02, and Agencia Estatal de Investigación del Gobierno de España (PID2020-114582RB-I00/ AEI / 10.13039/501100011033). J. Sierra thanks UTB for a post-graduate scholarship.Peer ReviewedPostprint (published version

Optical implementation of multifocal programmable lens with single and multiple axes

In this work we analyse the generation of a diffractive optical element (DOE) consisting of a multifocal Fresnel lens by means of an LCoS (liquid cristal on silicon) spatial light modulator (SLM). The multifocal lens is composed of a set of lenses of different focal length that share a common optical axis (coaxial combination) or have different axes in parallel (multi-axis combination). For both configurations, we present several ways to combine the phase distributions for three lenses with different focal lengths (f1, f2, f3), into a single-phase distribution addressed to the SLM. Numerical simulations were carried out along with the experimental analysis to corroborate the results.This research was supported by Ministerio de Ciencia e Innovación and FEDER funds under project DPI2009-08879.Peer ReviewedPostprint (published version

Codificación de la función de fase de una lente compuesta multifocal presentada por un modulador LCoS

Los autores agradecen la colaboración de J. Otón y el apoyo económico del Ministerio de Ciencia e Innovación así como de los fondos FEDER al proyecto DPI2006-05479.Peer ReviewedPostprint (published version

The application of digital techniques to an automatic radar track extraction system

SIGLEAvailable from British Library Document Supply Centre- DSC:D92897 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Double glazing for heat and sound insulation

SIGLEGBUnited Kingdo