Search results for "Òptica Aparells i instruments"
showing 10 items of 22 documents
Integral-Imaging display from stereo-Kinect capture
2017
In this paper, we propose a new approach in order to improve the quality of microimages and display them onto an integral imaging monitor. Our main proposal is based on the stereo-hybrid 3D camera system. Originally, hybrid camera system has dissimilarity itself. We interpret our method in order to equalize the hybrid sensor's characteristics and 3D data modification strategy. We generate integral image by using synthetic back-projection mapping method. Finally, we project the integral image onto our proposed display system. We illustrate this procedure with some imaging experiments in order to prove an advantage of our approach.
Integral imaging with Fourier-plane recording
2017
Integral Imaging is well known for its capability of recording both the spatial and the angular information of threedimensional (3D) scenes. Based on such an idea, the plenoptic concept has been developed in the past two decades, and therefore a new camera has been designed with the capacity of capturing the spatial-angular information with a single sensor and after a single shot. However, the classical plenoptic design presents two drawbacks, one is the oblique recording made by external microlenses. Other is loss of information due to diffraction effects. In this contribution report a change in the paradigm and propose the combination of telecentric architecture and Fourier-plane recordin…
View images with unprecedented resolution in integral microscopy
2018
Integral microscopy is a novel technique that allows the simultaneous capture of multiple perspective images of microscopic samples. This feature is achieved at the cost of a significant reduction of the spatial resolution. In fact, it is assumed that in the best cases the resolution is reduced by a factor that is not smaller than ten, what poses a hard drawback to the utility of the technique. However, to the best of our knowledge, this resolution limitation has never been researched rigorously. For this reason, the aim of this paper is to explore the real limitations in resolution of integral microscopy and to obtain optically, without the need of any image-processing algorithm, perspecti…
Response of the aging eye to first day of modern material contact lens wear
2018
Objectives: To investigate the ocular surface of an aged population wearing a daily disposable contact lens over their first day of wear. Methods: Forty eyes from forty presbyopic subjects were fitted a daily CL (Delefilcon A). Tear osmolarity, tear meniscus area (TMA) and ocular surface aberrations (total higher order root means square (RMS)) were assessed at baseline (t0), at 20 minutes (t1) and after 8 hours (t2) of wear. Fluorescein corneal and conjunctival staining and tear break up time (TBUT) were performed at t0 and t2. Results: No statistically significant changes were found between t0, t1 and t2 for TMA, and between t0 and t2 for fluorescein corneal and conjunctival staining. TBUT…
A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop
2013
We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40-1.442, respectively, are demonstrated. We estimate a long range resolut…
GPU-accelerated integral imaging and full-parallax 3D display using stereo-plenoptic camera system
2019
Abstract In this paper, we propose a novel approach to produce integral images ready to be displayed onto an integral-imaging monitor. Our main contribution is the use of commercial plenoptic camera, which is arranged in a stereo configuration. Our proposed set-up is able to record the radiance, spatial and angular, information simultaneously in each different stereo position. We illustrate our contribution by composing the point cloud from a pair of captured plenoptic images, and generate an integral image from the properly registered 3D information. We have exploited the graphics processing unit (GPU) acceleration in order to enhance the integral-image computation speed and efficiency. We…
Digital holographic microscopy as a screening technology for diabetes
2019
Label-free quantitative phase imaging (QPI) is the hallmark of digital holographic microscopy (DHM). One of the most interesting medical applications of QPI-DHM is that it can be used to analyze illnesses in which the refractive index or/and the morphology of cells/tissues are distorted, from the acquisition of a single image. In this contribution, we obtain the phase maps of red blood cells (RBCs) samples of patients suffering from diabetes mellitus type 1 (DM1) by using a DHM. Our experimental results show that the measured phase values are significantly different between control non-diabetic and diabetic patients. The high correlation coefficient between the phase and the glycated hemogl…
Digital holographic microscopy for diabetes screening
2016
A digital holographic microscope operating in telecentric mode could be used to diagnose diabetes and evaluate long-term glycemic control in patients with diabetes.
Phase-shifting by means of an electronically tunable lens: quantitative phase imaging of biological specimens with digital holographic microscopy
2016
The use of an electronically tunable lens (ETL) to produce controlled phase shifts in interferometric arrangements is shown. The performance of the ETL as a phase-shifting device is experimentally validated in phase-shifting digital holographic microscopy. Quantitative phase maps of a section of the thorax of a Drosophila melanogaster fly and of human red blood cells have been obtained using our proposal. The experimental results validate the possibility of using the ETL as a reliable phase-shifter device.
Accurate single-shot quantitative phase imaging of biological specimens with telecentric digital holographic microscopy
2014
The advantages of using a telecentric imaging system in digital holographic microscopy (DHM) to study biological specimens are highlighted. To this end, the performances of nontelecentric DHM and telecentric DHM are evaluated from the quantitative phase imaging (QPI) point of view. The evaluated stability of the microscope allows single-shot QPI in DHM by using telecentric imaging systems. Quantitative phase maps of a section of the head of the drosophila melanogaster fly and of red blood cells are obtained via single-shot DHM with no numerical postprocessing. With these maps we show that the use of telecentric DHM provides larger field of view for a given magnification and permits more acc…