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Nicolae Bălcescu, Romania

Jipa F.,National Institute for Laser, Plasma and Radiation Physics | Dinescu A.,National Institute for Microtechnology | Filipescu M.,National Institute for Laser, Plasma and Radiation Physics | Anghel I.,National Institute for Laser, Plasma and Radiation Physics | And 3 more authors.
Optics Express | Year: 2014

A new near-field processing method by femtosecond laser ablation using photoresist enhancing masks is numerically and experimentally investigated. Periodical structures with 2 μm pitch, 1 μm width and 300 nm height, created in polymethyl methacrylate photoresist by e-beam lithography, were used to intensify the incident laser radiation. The near-field distribution and the intensification factor of the optical radiation were computed using the Finite-Difference-Time-Domain numerical simulations. The pattern of the photoresist mask was imprinted on the surface of a silicon wafer. Using a single infrared femtosecond laser pulse, uniform and continuum grooves with the width in the range of 250 nm were obtained on large silicon surface. © 2014 Optical Society of America. Source


Mihailescu M.,Polytechnic University of Bucharest | Preda L.,Polytechnic University of Bucharest | Kusko C.,National Institute for Microtechnology
Applied Optics | Year: 2014

Helical phase distributions used for optical information transfer increase its capacity by offering a characteristic spatial intensity arrangement for the diffracted beam. Here we propose the superposition between helical phase distribution with an axicon type. They form a composed object placed in the object armto generate holographic masks. The diffracted patterns from these masks exhibit asymmetric shapes and peaks along the optical axis, with two kinds of spots, which contain independent or combined information from both phase distribution constructive parameters. To read these parameters based only on the diffraction patterns analysis, we generate the match reading masks (RMs) to be inserted in the optical path. In this proof-of-concept experiment, we demonstrate that one can sort constructive parameter values of each phase distribution, from both kinds of spots, using specific RMs. © 2014 Optical Society of America. Source


Mihailescu M.,National Institute for Microtechnology | Mihailescu M.,Polytechnic University of Bucharest | Gheorghiu A.,Polytechnic University of Bucharest | Popescu R.-C.,Polytechnic University of Bucharest
Proceedings of the Romanian Academy Series A - Mathematics Physics Technical Sciences Information Science | Year: 2013

In this paper we present our study regarding changes of human red blood cells (RBCs) immersed in solutions with different tonicity, monitored using digital holographic microscopy in order to connect their dimensions with the deformation states. We started with experimental images acquisition followed by our image processing procedure, which simultaneously provides information collected from more than one hundred cells from several images based on data from single cell level, and outputs are histograms after the main cell characteristics: minor radius, eccentricity, sphericity coefficient linked with the deformation states on three axes. It is also discussed how different digital filters are used for a better identification of the center and border of each cell. Source


Mihailescu M.,Polytechnic University of Bucharest | Paun I.A.,Polytechnic University of Bucharest | Scarlat E.I.,Polytechnic University of Bucharest | Grigorescu I.,Polytechnic University of Bucharest | And 2 more authors.
2015 11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015 | Year: 2016

The phase images of cervical cells were obtained in digital holographic microscopy to establish the cells 3D characteristics as criteria for information quantification and cells classification. We introduced a simple approach for the cells overlapping regions based on the focalization criteria. © 2015 IEEE. Source


Mihailescu M.,Polytechnic University of Bucharest | Kusko C.,National Institute for Microtechnology | Preda L.,Polytechnic University of Bucharest
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

We generated holographic masks starting with the interference between the reference beam and the signal beam, which is diffracted by the object. We investigate additive and multiplicative combinations between conical and helical phase distributions as compound objects to be inserted in the signal beam. We explored experimentally the dynamics of the diffracted intensity patterns, in two and three dimensions, after these holographic masks are addressed onto a programmable spatial light modulator. The diffracted intensity spatial arrangement contain information about constructive parameters used for holographic masks generation and exhibit asymmetric shapes and peaks along the optical axis in all analyzed compound objects. We introduce a reading mask in the optical path and, by analyzing changes of the spatial distribution in the final diffracted intensity arrangement, is possible to read the values of the constructive parameters. The generation of these reading masks in each case is discussed. © 2014 SPIE. Source

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