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Publications

Publications by CAP

2014

FEM simulation and experimental determination of the temperature profile of nanoparticles excited by laser radiation

Authors
Rodrigues, NFG; Rosa, CC; Coelho, JMP;

Publication
SECOND INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
Cancer cells can be easily killed when they reach a temperature above 40 degrees. This is known as hyperthermia and the incorporation of nanoparticles (NPs) is helpful to locally rise the temperature. The local heating of NPs could also be used to deliver drugs encapsulated in a specific location inside a body. To achieve the local heating it is necessary to know the temperature profile of the NPs when excited by laser radiation. The COMSOL software was used to simulate the temperature profile of the NPs in an aqueous solution (the cells are mainly composed of water). An analysis is made regarding the temperature rise for different irradiation parameters, NPs concentration and the corresponding potential of locally affecting cancerous cells without significantly affecting adjacent healthy cells.

2014

Design and optimization of a spectrometer for Spectral Domain Optical Coherence Tomography

Authors
Hosseiny, H; Rosa, CC;

Publication
SECOND INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
There are several factors such as the chosen optical source, central wavelength, spectral bandwidth, spectrometer optical components and the detector specifications that affect the overall performance of a spectral domain optical coherence tomography (SD-OCT) imaging system. Among these factors a good design and implementation of the spectrometer is of paramount importance as it directly affects the system resolution, sensitivity fall-off, maximum imaging depth, SNR and in general the system performance. This study demonstrates the design steps and some considerations during the design of a spectrometer. The imaging performance of this design is assessed. The obtained experimental results prove an improvement of the overall performance of the common path SD-OCT imaging system and agree with the expected outcome from the design stage.

2014

Teaching Optics with the centennial universal lantern

Authors
Joao Carvalhal, MJ; Monteiro, M; Marques, MB;

Publication
12TH EDUCATION AND TRAINING IN OPTICS AND PHOTONICS CONFERENCE

Abstract
A projection apparatus was bought in 1909 by the Physics Cabinet of the Polytechnic Academy (predecessor to the University of Porto's Faculty of Science) in order to present various physics experiments, mostly in the realm of Optics, to a large student audience. A stout and impressive mahogany and brass piece, with a voltaic arc lighting system, it was manufactured by the firm E. Leybold's Nachfolger, based in Chemnitz (Germany), already with a worldwide reputation as a supplier of teaching instruments and equipment to superior schools and universities. It was sold along with an extensive set of accessories, allowing for demonstrations in geometrical optics, spectrum analysis, interferometry, diffraction, polarization and double refraction. Two extra attachments, one for projecting microscopic objects, and the other for the projection of gypsum preparations in polarized light, added to the versatility of this lantern, appropriately dubbed of universal use. Both apparatus and accessories are presently to be found in the collection of the Museum of Science of our University. On studying them, we have come to the conclusion that many classical experiments in Optics may be displayed, without great effort and in an attractive manner. The adaptation to present day usage takes no more than the replacement of the lantern's voltaic arc by a suitable and safer light source. It so happens that a hundred-year old projection apparatus, fitted with a set of purposely designed add-ons, becomes so effective as its modern counterparts.

2014

Limits of spectral resolution in optical measurements

Authors
Marques, MB;

Publication
SECOND INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
Nowadays a growing number of scientists relies on optical spectral measurements for their research. The market is full of new plug-and-play equipment for spectral analysis that take the fuss out of the measurements. As with other instruments (computers, lasers, etc.) the researcher doesn't need any longer to work with someone with a post-graduate formation on the technology to be able to do excellent research. But, as in every instrument, there are limitations on the instrument use that affect its precision and resolution. Currently there is in the market a large variety of equipment for spectral measurements. They range from the huge long focal length double pass monochromators to the small pocket size USB connected array spectrometers. The different configurations have different sensitivities on the light input system, light intensity, coherence, polarization, etc. In this talk we will discuss a few of the limitations in spectral measurements that can be found in experimental setups.

2014

Post-processing fibers for sensing applications

Authors
Frazão, O; Ferreira, MS; André, RM; Silva, SO; Marques, MB; Santos, JL;

Publication
Optical Sensors, 2014

Abstract
A review in fiber post-processing for sensing applications is presented. The review is divided in three parts. Tapers devices, chemical etching for Fabry-Perot cavities and focused ion beam (FIB) as post-processing applied in optical fibers are considered. The most recent results as sensing elements are shown. © 2014 OSA.

2014

Solid to liquid light: Soliton dynamics using GPU computing

Authors
Guerreiro, A; Silva, NA;

Publication
SECOND INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
In this paper we address soliton-soliton interactions in a nonlinear cubic-quintic optic media, using for that purpose numerical methods and high performance graphics processor unit (GPU) computing. We describe an implementation of GPU-based computational simulations of the generalized Nonlinear Schrodinger Equation, obtaining simulations more than 40 times faster relative to CPU-based simulations, especially in the multidimensional case. We focus our attention in the study of soliton collisions and scattering phenomena that, offering the possibility of steering light with light, open a path towards future optical devices.

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