Practical guide for setting up a Fourier light-field microscope, Appl. Opt. 62, 4228 (2023)

Apractical guide for the easy implementation of a Fourier light-field microscope is reported. The Fourier light-field concept applied to microscopy allows the capture in real time of a series of 2D orthographic images of microscopic thick dynamic samples. Such perspective images contain spatial and angular information of the light-field emitted by the sample.Afeature of this technology is the tight requirement of a double optical conjugation relationship, and also the requirement of NA matching. For these reasons, the Fourier light-field microscope being a non-complex optical system, a clear protocol on howto set up the optical elements accurately is needed. In this sense, this guide is aim…

Off-axis Digital Holographic Microscopy: practical design parameters for operating at diffraction limit

The utilization of microscope objectives (MOs) in digital holographic microscopy (DHM) has associated effects that are not present in conventional optical microscopy. The remaining phase curvature, which can ruin the quantitative phase imaging, is the most evident and analyzed. As phase imaging is considered, this interest has made possible the development of different methods of overcoming its undesired consequences. Additionally to the effects in phase imaging, there exist a set of less obvious conditions that have to be accounted for as MOs are utilized in DHM to achieve diffraction-limit operation. These conditions have to be considered even in the case in which only amplitude or intens…

Full parallax 3D display from Kinect v1 and v2

We exploit the two different versions of Kinect, v1 and v2, for the calculation of microimages projected onto integral-imaging displays. Our approach is based on composing a three-dimensional (3-D) point cloud from a captured depth map and RGB information. These fused 3-D maps permit to generate an integral image after projecting the information through a virtual pinhole array. In our analysis, we take into account that each of the Kinect devices has its own inherent capacities and individualities. We illustrate our analysis with some imaging experiments, provide the distinctive differences between the two Kinect devices, and finally conclude that Kinect v2 allows the display of 3-D images …

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Scanning microscopy with spatial sampling of the detector plane

We present the implementation of a confocal scanning microscope in which the signal detection is performed through a matrix sensor, specifically, a CCD camera. This kind of detection has several advantages over the conventional detection in confocal microscopes. One of those advantages is the possibility to recover information of the sample that vanishes when the confocal image is directly acquired by the integration of light into a signal. We demonstrate the applicability of the system which allows implementing super-resolution techniques in a very easy manner.

Enhancing spatial resolution in digital holographic microscopy by biprism structured illumination

In a recent Letter by Seo et al. [Opt. Lett. 37, 4976 (2012)], the numerical correction of the quadratic phase distortion introduced by the microscope objective in digital holographic microscopy (DHM) has been presented. In this comment, we would like to draw to the attention of the authors and the readers in general that this approach could not be the optimal solution for maintaining the accuracy of the quantitative phase via DHM. We recall that the use of telecentric imaging systems in DHM simplifies the numerical processing of the phase images and produces more accurate measurements.

Diabetes screening by telecentric digital holographic microscopy

Diabetes is currently the world's fastest growing chronic disease and it is caused by deficient production of insulin by the endocrine pancreas or by abnormal insulin action in peripheral tissues. This results in persistent hyperglycaemia that over time may produce chronic diabetic complications. Determination of glycated haemoglobin level is currently the gold standard method to evaluate and control sustained hyperglycaemia in diabetic people. This measurement is currently made by high-performance liquid chromatography, which is a complex chemical process that requires the extraction of blood from the antecubital vein. To reduce the complexity of that measurement, we propose a fully-optica…

Fast and robust wave optics-based reconstruction protocol for Fourier lightfield microscopy

Fourier lightfield microscopy (FLMic) is a powerful technique to record 3D images of thick dynamic samples. Belonging FLMic to the general class of computational imaging techniques, its efficiency is determined by several factors, like the optical system, the calibration process, the reconstruction algorithm, or the computation architecture. In the case of FLMic the calibration and the reconstruction algorithm should be fully adapted to the singular features of the technique. To this end, and concerning the reconstruction, we discard the use of experimental PSFs, and propose the use of a synthetic one, which is calculated on the basis of paraxial optics and taking into account the equal inf…

Photoelastic Analysis of Partially Occluded Objects With an Integral-Imaging Polariscope

Polariscopes are the basic instruments used for the analysis of the stress state of transparent materials. Polarized light passing through a 3D object carries the integrated effect of the stress field along the light path. Therefore, conventional polariscopes are not able to discern the stress state of objects involving multiple plates with mutual occlusions. In this paper we propose a novel experimental system for three-dimensional stress analysis based on the combination of a polariscope and Synthetic Aperture Integral Imaging technique. Experimental results show the system's ability to recover the information of the stress distribution of a set of plates located at different depths havin…

Óptica Geométrica. Espejos y Lentes

Utilización de una maleta con elementos ópticos para demostraciones de óptica geométrica. LFuncionamiento de espejos y lentes. Producción: Centre de Formació i Qualitat Manuel Sanchis Guarner (http://www.uv.es/cfq).

Demo 43. Espejos esféricos

Objetivo: Obtener una imagen real por reflexión doble en dos espejos esféricos de idéntico radio de curvatura.