Search results for "Òptica Aparells i instruments"
showing 10 items of 22 documents
The Lightfield Microscope Eyepiece
2021
Lightfield microscopy has raised growing interest in the last few years. Its ability to get three-dimensional information about the sample in a single shot makes it suitable for many applications in which time resolution is fundamental. In this paper we present a novel device, which is capable of converting any conventional microscope into a lightfield microscope. Based on the Fourier integral microscope concept, we designed the lightfield microscope eyepiece. This is coupled to the eyepiece port, to let the user exploit all the host microscope’s components (objective turret, illumination systems, translation stage, etc.) and get a 3D reconstruction of the sample. After the optical design, …
Recent Advances in the Capture and Display of Macroscopic and Microscopic 3-D Scenes by Integral Imaging
2017
The capture and display of images of 3-D scenes under incoherent and polychromatic illumination is currently a hot topic of research, due to its broad applications in bioimaging, industrial procedures, military and surveillance, and even in the entertainment industry. In this context, Integral Imaging (InI) is a very competitive technology due to its capacity for recording with a single exposure the spatial-angular information of light-rays emitted by the 3-D scene. From this information, it is possible to calculate and display a collection of horizontal and vertical perspectives with high depth of field. It is also possible to calculate the irradiance of the original scene at different dep…
Terapia visual: ¿por qué existe? ¿Cuándo es aconsejable?
1998
La evolución de la optometría ha sido importante en los últimos años. Cada día se habla más de posibles especialidades. Una de ellas es la Terapia visual sin embargo aún existen Ópticos optometristas que se sorprenden cuando oyen hablar de tratamiento visual mediante ejercicios y los resultados satisfactorios que se han llegado a obtener en muchos casos. El objetivo del presente trabajo es hablar sobre el por qué de la terapia visual así como de la necesidad progresiva que la sociedad actual tiene de estos servicios profesionales, debido a las fuertes demandas visuales con las que se encuentra una persona a lo largo de su vida.
Sampling Rate in the Dynamic Speckle Analysis
2022
AbstractDynamic laser speckle and its biological version (biospeckle laser) have been used in many areas of knowledge. Its non-invasive approach allows the application in advantage regarding those that need contact or damage the analyzed sample. However, one needs the sharp adjust of the image acquiring and processing. In this article, we show how the variation of sampling rate in a dynamic speckle analysis affects the value of dynamic speckle indexes concerning the absolute value of the differences index, the temporal speckle standard deviation index, and the temporal speckle mean index. We show that the dynamic speckle index value changes its maximum excursion with the variation of sampli…
Synchronized photonic modulators driven by surface acoustic waves
2013
Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180 degrees-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms. (C) 2013 Optical Society of America
Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector
2018
CR-39 nuclear track material is frequently used for the detection of protons accelerated in laser-plasma interactions. The measurement of track densities allows for determination of particle angular distributions, and information on the kinetic energy can be obtained by the use of passive absorbers. We present a precise method of measuring spectral distributions of laser-accelerated protons in a single etching and analysis process. We make use of a one-to-one relation between proton energy and track size and present a precise calibration based on monoenergetic particle beams. While this relation is limited to proton energies below 1 MeV, we show that the range of spectral measurements can b…
Mapping electron-beam-injected trapped charge with scattering scanning near-field optical microscopy.
2016
Scattering scanning near-field optical microscopy (s-SNOM) has been demonstrated as a valuable tool for mapping the optical and optoelectronic properties of materials with nanoscale resolution. Here we report experimental evidence that trapped electric charges injected by an electron beam at the surface of dielectric samples affect the sample-dipole interaction, which has direct impact on the s-SNOM image content. Nanoscale mapping of the surface trapped charge holds significant potential for the precise tailoring of the electrostatic properties of dielectric and semiconductive samples, such as hydroxyapatite, which has particular importance with respect to biomedical applications. The meth…
Shaded-Mask Filtering for Extended Depth-of-Field Microscopy
2013
This paper proposes a new spatial filtering approach for increasing the depth-of-field (DOF) of imaging systems, which is very useful for obtaining sharp images for a wide range of axial positions of the object. Many different techniques have been reported to increase the depth of field. However the main advantage in our method is its simplicity, since we propose the use of purely absorbing beam-shaping elements, which allows a high focal depth with a minimum modification of the optical architecture. In the filter design, we have used the analogy between the axial behavior of a system with spherical aberration and the transverse impulse response of a 1D defocused system. This allowed us the…
Presbyopia and the aging eye: Existing refractive approaches and their potential impact on dry eye signs and symptoms.
2020
Every part of the human body is subject to aging, including the eye. Increased prevalence of dry eye disease with age is widely acknowledged: aging threatens ocular surface homeostasis, altering the normal functioning of the lacrimal functional unit and potentially leading to signs and symptoms of dry eye. Parallelly, two additional degenerative processes take place within the crystalline lens, leading to presbyopia and cataractogenesis. With continuously increasing life expectancies both conditions are expected to impact society further. Correction strategies for presbyopia and cataracts either directly or indirectly challenge ocular surface additionally. On one hand, contact lens presbyop…
Evaluation of the use of wavefront encoding to reduce depth-induced aberration in structured-illumination microscopy
2018
Three-dimensional imaging is affected by depth-induced spherical aberration (SA) when imaging deep into an optically thick sample. In this work, we evaluate the impact of SA on the performance of incoherent grating-projection structured illumination microscopy (SIM). In particular, we analyze the reduction of the contrast in the structured pattern and compare the reconstructed SIM images for different amounts of SA. In order to mitigate the impact of SA, we implement and evaluate in SIM a wavefront encoded imaging system using a square cubic (SQUBIC) phase mask, an approach shown previously to be successful in conventional microscopy.