Prof. Ashraf Fathy El-Sherif Profile

Prof. Ashraf Fathy El-Sherif

Associate Professor at Military Technical College

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Author

Publications (24)

SPIE Journal Paper | 25 January 2018

Design and simulation of MEMS-actuated adjustable optical wedge for laser beam scanners

Ahmed Bahgat, Ahmed Zaki, Mohamed Abdo Mohamed, Ashraf Fathy El Sherif

JM3, Vol. 17, Issue 01, 015501, (January 2018) https://doi.org/10.1117/12.10.1117/1.JMM.17.1.015501

KEYWORDS: Laser scanners, Laser optics, Actuators, 3D scanning, Optical simulations, Finite element methods, Microopto electromechanical systems, Refraction, Polygon scanners, Scalable video coding

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Proceedings Article | 15 March 2016 Paper

Active modulation of laser coded systems using near infrared video projection system based on digital micromirror device (DMD)

Aly Khalifa, Hussein Aly, Ashraf El-Sherif

Proceedings Volume 9761, 97610A (2016) https://doi.org/10.1117/12.2214300

KEYWORDS: Near infrared, Digital micromirror devices, Modulation, Projection systems, Signal processing, Laser systems engineering, Digital signal processing, Digital Light Processing, Video, Hardware testing, Mirrors, Semiconductor lasers, Pulsed laser operation, Photography

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Proceedings Article | 8 March 2016 Paper

Design and implementation of a deception jamming system for laser receivers

Ahmed Bahgat, Ashraf El-Sherif, Yaser El-Sharkawy

Proceedings Volume 9768, 97681M (2016) https://doi.org/10.1117/12.2206011

KEYWORDS: Laser countermeasures, High power lasers, Light emitting diodes, Signal to noise ratio, Digital signal processing, Receivers, Phase shifts, Pulsed laser operation, Laser scattering, Signal processing, Metals, Laser applications, Polymers, Signal detection, Laser systems engineering

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Proceedings Article | 26 March 2015 Paper

Underwater laser detection system

Walid Gomaa, Ashraf El-Sherif, Yasser El-Sharkawy

Proceedings Volume 9342, 934221 (2015) https://doi.org/10.1117/12.2080181

KEYWORDS: Target detection, Laser sources, Submerged target detection, Metals, Imaging systems, Absorption, Light sources, Laser systems engineering, Scattering, Signal attenuation

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Proceedings Article | 18 February 2014 Paper

Characterization, diagnosis and ablation of human teeth using blue laser at 457 nm

Ashraf El-Sherif, Walid Gomaa, Yasser El-Sharkawy

Proceedings Volume 8929, 892902 (2014) https://doi.org/10.1117/12.2038590

KEYWORDS: Teeth, Absorption, Dental caries, Laser tissue interaction, Laser ablation, Spectroscopy, Tissues, Laser sources, Laser dentistry, Optical properties

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SPIE Journal Paper | 27 January 2014 Open Access

High-performance near-infrared imaging for breast cancer detection

Yasser El-Sharkawy, Ashraf El-Sherif

JBO, Vol. 19, Issue 01, 016018, (January 2014) https://doi.org/10.1117/12.10.1117/1.JBO.19.1.016018

KEYWORDS: Tumors, Thermography, Tissues, Laser tissue interaction, Breast cancer, Near infrared, Tissue optics, Breast, Mammography, Absorption

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SPIE Journal Paper | 24 January 2014

Studying the effect of zeolite inclusion in aluminum alloy on measurement of its surface hardness using laser-induced breakdown spectroscopy technique

Osama Khalil, Ilya Mingareev, Tobias Bonhoff, Ashraf El-Sherif, Martin Richardson, Mohamed Harith

OE, Vol. 53, Issue 01, 014106, (January 2014) https://doi.org/10.1117/12.10.1117/1.OE.53.1.014106

KEYWORDS: Aluminum, Laser induced breakdown spectroscopy, Zeolites, Magnesium, Laser processing, Spectroscopy, Silicon, Statistical analysis, Silicates, Plasma

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Proceedings Article | 9 March 2013 Paper

Silicon backside machining using a nanosecond 2-µm Tm:fiber laser

Lawrence Shah, Tobias Bonhoff, Thomas Ferhat, Ashraf El-Sherif, Mark Ramme, Christina C. Willis, Matthieu Baudelet, Pankaj Kadwani, Christian Gaida, Martin Gebhardt, Ilya Mingareev, Martin Richardson

Proceedings Volume 8612, 861207 (2013) https://doi.org/10.1117/12.2004878

KEYWORDS: Silicon, Semiconductor lasers, Semiconducting wafers, Oscillators, Laser ablation, Pulsed laser operation, Laser damage threshold, Laser applications, Laser systems engineering, Optical parametric oscillators

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Proceedings Article | 6 March 2013 Paper

High efficient, high peak power of 18kW with 4ns pulses of diode pumped passive Q-switched and self Q-switched Nd: YVO4] laser at both 1064nm using Cr:YAG and 532 nm using ktp crystals

Ashraf El-Sherif, Mahmoud Talaat

Proceedings Volume 8599, 859927 (2013) https://doi.org/10.1117/12.2007665

KEYWORDS: Neodymium, Crystals, Semiconductor lasers, Laser crystals, Q switched lasers, Ferroelectric materials, Diodes, Neodymium lasers, Mirrors, Laser systems engineering

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Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designation systems. This paper presents theoretical calculations using Advanced Dynamics Professional LASCAD software and experimental studies for a high power pigtailed fiber diode laser module of 8 W operating at 808 nm with a specially designed high efficiency cooling system, end pumped high-efficiency Nd:YVO₄ laser of 3×3×10 mm rod and overall cavity length of 44 mm. An optical to optical slope efficiency of around 76%, the final conversion efficiency of 60% and a maximum average output power of 4.11 W at 1064 nm laser were investigated with a high single-mode beam quality factor M² of < 1.1, and the lowest threshold pumping power of 800 mW was measured, which was in agreement with the theoretical calculations of 776 mW. A high power second harmonic Nd:YVO₄ CW laser at 532 nm (green laser) was achieved with an optical to optical slope efficiency of 66% and a final conversion efficiency of 56% using a 5×5×8 mm KTP crystal placed intracavity of the same 1064 nm CW laser with water cooling system. The green laser average output power of 3.38 W at incident diode laser power of 6 W was measured. To the best of our knowledge a self Q-switching effects was generated in Nd:YVO₄ laser by changing the cavity dimensions and the position of the intracavity KTP crystal at certain regime of operation for the first time, in which the cavity length is reduced to be 30 mm and the distance between Nd:YVO₄ rod and KTP crystal is only 1mm. Self Qswitched laser pulse at 532 nm with high peak power of 96 W, pulse width of 88 ns at FWHM and repetition rate of 400 kHz was achieved. Experimental studies of a passive Q-switched Nd:YVO₄ laser using Cr:YAG crystal with three different transmissions of 30%, 40% and 70% were investigated. Passive Q-switched laser pulse at 1064 nm and narrow line width of less than 1.5 nm with highest peak power of nearly 18 kW, short pulse width of less than 4 ns at FWHM and higher repetition rate of 45 kHz using Cr:YAG with transmission of 30% was achieved for the first time. The main application for the investigated effect is generation of an efficient and high repetitive high peak power self Q-switched second harmonic Nd:YVO₄ laser system that can be realized without the need of using any of passive Q-switched semiconductor saturable absorber mirror SESAM.

Proceedings Article | 4 March 2013 Paper

Characterization of low cost optical imaging system based on optical holography

M. Darwiesh, Ashraf F. El Sherif

Proceedings Volume 8641, 86411U (2013) https://doi.org/10.1117/12.974895

KEYWORDS: Light emitting diodes, Semiconductor lasers, Holograms, Helium neon lasers, Optical imaging, Imaging systems, Diffusers, Green light emitting diodes, Blue light emitting diodes, Light sources

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Proceedings Article | 15 February 2012 Paper

Comparison between two active media Nd: YAG and Nd: YVO4 rods inside a cavity for producing a high-power 808nm diode end-pumping laser system

Ashraf El-Sherif, Khalid Hussein, Mahmoud Hassan, Mahmoud Talat

Proceedings Volume 8235, 82351P (2012) https://doi.org/10.1117/12.902906

KEYWORDS: Neodymium, Nd:YAG lasers, Crystals, Laser crystals, Semiconductor lasers, Diodes, Solid state lasers, YAG lasers, Diode pumped solid state lasers, Optical pumping

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Proceedings Article | 15 February 2012 Paper

Temperature effects on the operation and input/output wavelengths of a high-power fiber-coupled diode end pumped Nd:YVO4 laser

Ashraf El-Sherif

Proceedings Volume 8235, 82351O (2012) https://doi.org/10.1117/12.901947

KEYWORDS: Semiconductor lasers, Diodes, Temperature metrology, Neodymium lasers, Solid state lasers, Spectroscopy, Laser damage threshold, Crystals, Fiber coupled lasers, High power diode lasers

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Proceedings Article | 9 February 2012 Paper

Human teeth model using photoacoustic frequency response

Yasser El-Sharkawy, Ashraf El-Sherif

Proceedings Volume 8221, 82210J (2012) https://doi.org/10.1117/12.903854

KEYWORDS: Teeth, Photoacoustic spectroscopy, Tissues, Acoustics, Modulation, Pulsed laser operation, Laser sources, Tissue optics, Thermography, Absorption

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Proceedings Article | 9 February 2012 Paper

Experimental studies for improvement of thermal effects in a high-power fiber-coupled diode laser module operating at 808 nm

Ashraf El-Sherif, Khalid Hussein, Mahmoud Hassan, Mahmoud Talat

Proceedings Volume 8241, 824115 (2012) https://doi.org/10.1117/12.901945

KEYWORDS: Semiconductor lasers, Fluctuations and noise, Temperature metrology, Diodes, High power diode lasers, Thermography, Fiber lasers, Solid state lasers, Cooling systems, Sensors

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SPIE Journal Paper | 1 April 2011

Design and performance analysis of a tunable and self-pulsation diode pumped double-clad D-shaped Yb³⁺-doped silica fiber laser

Ashraf El-Sherif, Mohamed El-Tahlawy

OE, Vol. 50, Issue 04, 044201, (April 2011) https://doi.org/10.1117/12.10.1117/1.3562318

KEYWORDS: Fiber lasers, Ytterbium, Ions, Optical fibers, Absorption, Semiconductor lasers, Diodes, Reflectivity, Mirrors, Tunable lasers

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Proceedings Article | 22 February 2011 Paper

Effects of the source, surface, and sensor couplings and colorimetric of laser speckle pattern on the performance of optical imaging system

M. Darwiesh, Ashraf El-Sherif, Hatem El-Ghandour, Hussein Aly, A. Mokhtar

Proceedings Volume 7920, 792005 (2011) https://doi.org/10.1117/12.874074

KEYWORDS: Diffusers, Light emitting diodes, Speckle, Light sources, RGB color model, Helium neon lasers, Imaging systems, Optical imaging, Semiconductor lasers, Sensors

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Optical imaging systems are widely used in different applications include tracking for portable scanners; input pointing devices for laptop computers, cell phones, and cameras, fingerprint-identification scanners, optical navigation for target tracking, and in optical computer mouse. We presented an experimental work to measure and analyze the laser speckle pattern (LSP) produced from different optical sources (i.e. various color LEDs, 3 mW diode laser, and 10mW He-Ne laser) with different produced operating surfaces (Gabor hologram diffusers), and how they affects the performance of the optical imaging systems; speckle size and signal-to-noise ratio (signal is represented by the patches of the speckles that contain or carry information, and noise is represented by the whole remaining part of the selected image). The theoretical and experimental studies of the colorimetry (color correction is done in the color images captured by the optical imaging system to produce realistic color images which contains most of the information in the image by selecting suitable gray scale which contains most of the informative data in the image, this is done by calculating the accurate Red-Green-Blue (RGB) color components making use of the measured spectrum for light sources, and color matching functions of International Telecommunication Organization (ITU-R709) for CRT phosphorus, Tirinton-SONY Model ) for the used optical sources are investigated and introduced to present the relations between the signal-to-noise ratios with different diffusers for each light source. The source surface coupling has been discussed and concludes that the performance of the optical imaging system for certain source varies from worst to best based on the operating surface. The sensor /surface coupling has been studied and discussed for the case of He-Ne laser and concludes the speckle size is ranged from 4.59 to 4.62 μm, which are slightly different or approximately the same for all produced diffusers (which satisfies the fact that the speckle size is independent on the illuminating surface). But, the calculated value of signal-tonoise ratio takes different values ranged from 0.71 to 0.92 for different diffuser. This means that the surface texture affects the performance of the optical sensor because, all images captured for all diffusers under the same conditions [same source (He-Ne laser), same distances of the experimental set-up, and the same sensor (CCD camera)].

Proceedings Article | 19 February 2011 Paper

Laser ultrasound characterization of normal and decayed teeth by measuring elastic properties of surface layers

Yasser El-Sharkawy, Ashraf ElSherif

Proceedings Volume 7897, 78971K (2011) https://doi.org/10.1117/12.868322

KEYWORDS: Teeth, Acoustics, Laser tissue interaction, Tissues, Natural surfaces, Phase velocity, Signal attenuation, Absorption, Laser dentistry, Wave propagation

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Proceedings Article | 8 September 2010 Paper

Multivariate image analysis of laser-induced photothermal imaging used for detection of caries tooth

Ashraf El-Sherif, Wessam Abdel Aziz, Yasser El-Sharkawy

Proceedings Volume 7798, 77981R (2010) https://doi.org/10.1117/12.860032

KEYWORDS: Teeth, Dental caries, Thermography, RGB color model, Absorption, Laser tissue interaction, Image analysis, Cameras, Tissues, Principal component analysis

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Proceedings Article | 23 August 2010 Paper

Design and performance analysis of a tunable and self-pulsation diode pumped double-clad D-shaped Yb3+-doped silica fiber laser

Ashraf El-Sherif, Mohamed El-Tahlawy

Proceedings Volume 7789, 778911 (2010) https://doi.org/10.1117/12.860462

KEYWORDS: Fiber lasers, Ions, Absorption, Optical fibers, Ytterbium, Semiconductor lasers, Reflectivity, Diodes, Mirrors, Tunable lasers

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Proceedings Article | 28 February 2009 Paper

Optimization of a high-power fiber-coupled diode-end-pumped Nd:YVO4 solid state laser

Ashraf El-Sherif

Proceedings Volume 7193, 71930O (2009) https://doi.org/10.1117/12.808539

KEYWORDS: Neodymium lasers, Crystals, Laser crystals, Solid state lasers, Semiconductor lasers, Output couplers, Optical simulations, Diode pumped solid state lasers, Reflectivity, Diodes

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Proceedings Article | 11 February 2008 Paper

Laser-induced photothermal technique used for detection of caries in human tooth

Ashraf El-Sherif, Yasser El-Sharkawy

Proceedings Volume 6843, 68430B (2008) https://doi.org/10.1117/12.759157

KEYWORDS: Teeth, Dental caries, Tissues, Photoacoustic spectroscopy, Absorption, Thermography, Sensors, Acoustics, Pulsed laser operation, Transducers

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Proceedings Article | 18 June 2007 Paper

Designing a new optical sensor using wide band speckle patterns

Hatem El Ghandoor, Ashraf El Sherif, M. Darwish

Proceedings Volume 6616, 66161G (2007) https://doi.org/10.1117/12.724870

KEYWORDS: Speckle pattern, Light emitting diodes, Speckle, Sensors, Semiconductor lasers, Diffusers, Digital signal processing, Light sources, Optical sensors, Photography

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Proceedings Article | 15 March 2006 Paper

Evaluation of a high power Q-switched Tm³⁺-doped silica fiber laser operating near 2μm

Ashraf El-Sherif, Terence King

Proceedings Volume 6102, 61020R (2006) https://doi.org/10.1117/12.639870

KEYWORDS: Bragg cells, Fiber lasers, Thulium, Q switched lasers, Q switches, Q switching, Modulation, Crystals, Electrooptic modulators, Pulsed laser operation

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Proceedings Article | 15 February 2006 Paper

Diagnostic of human teeth using photoacoustic response

Yasser El-Sharkawy, Y. Badr, M. Gadallah, Ashraf El-Sherif

Proceedings Volume 6137, 613701 (2006) https://doi.org/10.1117/12.634879

KEYWORDS: Teeth, Photoacoustic spectroscopy, Transducers, Diagnostics, Laser dentistry, Michelson interferometers, Tissue optics, Statistical analysis, Acoustics, Signal detection

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Showing 5 of 24 publications

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