arXiv subjects

Ali Mahmoudi

Publications and source records attributed to Ali Mahmoudi.

5 recordsLinked to original sources

arXiv2019

Saliency Detection With Fully Convolutional Neural Network

Saliency detection is an important task in image processing as it can solve many problems and it usually is the first step in for other processes. Convolutional neural networks have been proved to be very effective on several image processing tasks such as classification, segmentation, semantic colorization and object manipulation. Besides, using the weights of a pretrained networks is a common practice for enhancing the accuracy of a network. In this paper a fully convolutional neural network which uses a part of VGG-16 is proposed for saliency detection in images.

cs.CV↗

arXiv2014

Zero Focal Shift in High Numerical Aperture Focusing of a Gaussian Laser Beam through Multiple Dielectric Interfaces

In this paper, focal shift of a Guassian laser beam tightly focused through several planar dielectric interfaces is discussed. It is shown that the focal shift and focus point can be changed by variation of refractive index mismatch and this shift could be positive or negative, and it is proportional to refractive index mismatch between coverglass and immersion medium. It is shown also that for every immersion medium(coverglass), focal shift could be removed for a continuous range of depths by choosing a coverglass (immersion medium) with appropriate refractive index.

physics.optics↗

arXiv2011

The effect of Immersion medium in optical tweezers

In this paper, we report on theoretical investigation of the effect of refractive index of immersion oil on the position of optimal depth and optical trap quality in optical tweezers. Using simple numerical calculation presented here, one can study the optical trapping in different samples, after multi interfaces and find the best choice of immersion oil for a particular case.

physics.optics↗

arXiv2007

Negative refraction of a three-dimensional metallic photonic crystal

A metamaterial with a negative effective index of refraction is made from a three-dimensional hexagonal lattice photonic crystal with a metallic basis embedded in foam. It has been simulated with Ansoft HFSSTM in a frequency range from 7.0 to 12.0 GHz. Simulated results tested experimentally and negative refraction verified in some frequencies. Experimental results are in excellent agreement with simulations.

physics.optics↗

arXiv2007

Analysis, Design and Fabrication of centimeter-wave Dielectric Fresnel Zone Plate Lens and reflector

Fresnel lens has a long history in optics. This concept at non-optical wavelengths is also applicable. In this paper we report design and fabrication of a half and quarter wave dielectric Fresnel lens made of Plexiglas, and a Fresnel reflector at 11.1 GHz frequency. We made two lenses and one reflector at same frequency and compare their gain and radiation pattern to simulated results. Some methods for better focusing action will be introduced.

physics.optics↗