Dr. Dhiraj K. Sardar Profile

Dr. Dhiraj K. Sardar

Professor at Univ of Texas at San Antonio

SPIE Involvement:

Author

Publications (27)

Proceedings Article | 12 March 2015 Paper

Effects of surface chemistry on the optical properties and cellular interaction of lanthanide-based nanoparticles

Francisco Pedraza, Julio Avalos, Lawrence Mimun, Brian Yust, Andrew Tsin, Dhiraj Kumar Sardar

Proceedings Volume 9339, 93390A (2015) https://doi.org/10.1117/12.2079943

KEYWORDS: Nanoparticles, Ions, Chemistry, Biomedical optics, Near infrared, Thulium, Absorption, Lanthanides, Optical properties, Photons

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Proceedings Article | 12 March 2015 Paper

Characterization of nanosecond pulse electrical field shock waves using imaging techniques

L. Chris Mimun, Bennett Ibey, Caleb Roth, Ronald Barnes, Dhiraj Sardar, Hope Beier

Proceedings Volume 9326, 93260S (2015) https://doi.org/10.1117/12.2079271

KEYWORDS: Electrodes, Cameras, Tungsten, Acoustics, Laser beam diagnostics, Visualization, Glasses, Electromagnetism, High speed cameras, Wave propagation

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Proceedings Article | 7 March 2014 Paper

Ultrasmall lanthanide-doped nanoparticles as multimodal platforms

Brian Yust, Francisco Pedraza, Dhiraj Sardar

Proceedings Volume 8956, 895608 (2014) https://doi.org/10.1117/12.2037389

KEYWORDS: Nanoparticles, Near infrared, Upconversion, Quantum efficiency, Magnetism, Absorption, Magnetic resonance imaging, Erbium, Neodymium, Biomedical optics

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Proceedings Article | 7 March 2014 Paper

NIR to NIR upconversion in KYb2F7: RE3+ (RE = Tm, Er) nanoparticles for biological imaging

F. Pedraza, B. Yust, A. Tsin, D. Sardar

Proceedings Volume 8956, 89560Q (2014) https://doi.org/10.1117/12.2037913

KEYWORDS: Nanoparticles, Near infrared, Erbium, Thulium, Upconversion, Quantum efficiency, Tissues, Absorption, Microscopes, Confocal microscopy

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Proceedings Article | 3 March 2014 Paper

Optoacoustic microscopy using laser beam deflection technique

E. Khachatryan, S. Maswadi, D. Tsyboulski, E. Barnes, D. Sardar, A. Oraevsky, K. Nash, R. Glickman

Proceedings Volume 8943, 89432T (2014) https://doi.org/10.1117/12.2040718

KEYWORDS: Laser beam diagnostics, Tissue optics, Ultrasonography, Acoustics, Microscopy, Objectives, Image resolution, Tissues, Transducers, Nanoparticles

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Optoacoustic microscopy (OAM) is an emerging technology combining the beneficial features of optical contrast and ultrasound resolution, to form a hybrid imaging technique capable of multi-scale, high-contrast and high-resolution imaging through optically scattering biological tissues. In the past 15 years, two system modifications have been developed for optoacoustic / photoacoustic microscopy: acoustic-resolution AR-OAM and optical-resolution OR-OAM. Typically, acoustic resolution systems can image deeper tissues structures, however, with resolution at least an order of magnitude worse than the systems of optical-resolution. It would be attractive for variety of biomedical applications to attain high (submicron) resolution at a depth exceeding the present limit of the optical resolution optoacoustic microscopy. Here we introduce a novel, all-optical method for OAM, in which not only thermal energy deposition, but also optoacoustic signal detection is achieved optically. In our design the probe laser beam was used as an ultrawide-band ultrasonic transducer. In this method the acoustic pressure wave amplitude is proportional to the angle of deflection of the probing CW laser beam incident on a balanced dual photodiode. Such laser beam deflection (LBD) method overcomes the limitations of conventional piezoelectric ultrasound transducers and optical interferometers. LBD method allows one to use high numerical aperture objectives for better focusing, avoid distortions associated with the system elements that separate optical and acoustic paths, and provides better sensitivity than any optical interferometer. It also provides a non-contact method that is insensitive to optical and acoustic artifacts typical of backward mode of optoacoustic imaging. The LBD sensitivity depends on a large number of system parameters such as probe beam power, spot size, interaction length, optical refraction index of the coupling medium, laser wavelength, photodiode sensitivity, proximity to the optoacoustic source, and thus, can be optimized. The basic setup of OR-LBD-OAM shows high sensitivity competitive with commercial ultrasonic transducers. We report first images of biological cells and tissues obtained using this technique.

Proceedings Article | 4 March 2013 Paper

Plasmon-enhanced upconversion in Yb3+/Er3+ doped inY2O3

Madhab Pokhrel, Jianhui Yang, G. Kumar, Brian Yust, Dhiraj Sardar

Proceedings Volume 8641, 86410K (2013) https://doi.org/10.1117/12.2004858

KEYWORDS: Gold, Silica, Upconversion, Near field, Scattering, Absorption, Plasmons, Coating, Quantum efficiency, Nanorods

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Proceedings Article | 19 February 2013 Paper

Rare Earth doped nanoparticles in imaging and PDT

Brian Yust, Dhiraj Sardar, Lawrence Mimun, Ajith Gangadharan, Andrew Tsin

Proceedings Volume 8594, 85940D (2013) https://doi.org/10.1117/12.2004939

KEYWORDS: Nanoparticles, Upconversion, Photodynamic therapy, Near infrared, Biomedical optics, Infrared imaging, Infrared radiation, Photons, Ions, Infrared photography

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Proceedings Article | 21 February 2012 Paper

Energy converting material for solar cell application

Madhab Pokhrel, G Kumar, Dhiraj Sardar

Proceedings Volume 8256, 82561Q (2012) https://doi.org/10.1117/12.906835

KEYWORDS: Upconversion, Solar cells, Erbium, Solar energy, Ytterbium, Absorption, Crystals, Photons, Luminescence, Infrared radiation

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Proceedings Article | 6 February 2012 Paper

Infrared excited Yb:Er: Y2O2S phosphors with intense emission for lighting applications

G. A. Kumar, Madhab Pokhrel, D. Sardar

Proceedings Volume 8278, 82780E (2012) https://doi.org/10.1117/12.906804

KEYWORDS: Ytterbium, Erbium, Upconversion, Luminescence, Absorption, Solid state physics, Infrared radiation, Electro optical modeling, Quantum efficiency, Biomedical optics

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Proceedings Article | 2 February 2012 Paper

Highly efficient phosphors in cancer sensing and PDT

Brian Yust, Lawrence Mimun, Dhiraj Sardar, Gangadharan Ajith Kumar, Peter Hornsby, Jason Rocha

Proceedings Volume 8233, 823312 (2012) https://doi.org/10.1117/12.908986

KEYWORDS: Nanoparticles, Atmospheric particles, Photodynamic therapy, Upconversion, Particles, Coating, Cancer, Ytterbium, Polymers, Molecules

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Proceedings Article | 2 February 2012 Paper

Utilizing nonlinear optical properties of nanoparticles for imaging and sensing

Brian Yust, Neema Razavi, Francisco Pedraza, Dhiraj Sardar

Proceedings Volume 8231, 82310H (2012) https://doi.org/10.1117/12.909009

KEYWORDS: Ferroelectric materials, Nanoparticles, Silver, Particles, Nonlinear optics, Phase conjugation, Absorption, Microscopy, Refractive index, Nanorods

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Proceedings Article | 12 February 2011 Paper

Phase conjugating nanomirrors: utilizing optical phase conjugation for imaging

Brian Yust, Dhiraj Sardar, Andrew Tsin

Proceedings Volume 7908, 79080G (2011) https://doi.org/10.1117/12.874293

KEYWORDS: Phase conjugation, Ferroelectric materials, Nanocrystals, Four wave mixing, Nanoparticles, Tissue optics, Biomedical optics, Scattering, Wave propagation, Absorption

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Proceedings Article | 11 February 2010 Paper

A comparison of methods for determining optical properties of thin samples

Brian Yust, Dhiraj Sardar, Andrew Tsin

Proceedings Volume 7562, 75620C (2010) https://doi.org/10.1117/12.841362

KEYWORDS: Absorption, Optical properties, Scattering, Particles, Near infrared, Oxides, Optical spheres, Tissues, Statistical modeling, Transmittance

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SPIE Journal Paper | 1 September 2007 Open Access

Bioluminescence measurements in mice using a skin window

Qin Huang, Victor Acha, Raylon Yow, Erik Schneider, Dhiraj Sardar, Peter Hornsby

JBO, Vol. 12, Issue 05, 054012, (September 2007) https://doi.org/10.1117/12.10.1117/1.2795567

KEYWORDS: Bioluminescence, Skin, Kidney, Optical testing, Biosensors, Tissues, Proteins, Fiber optics, Photon counting, Green fluorescent protein

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Proceedings Article | 20 February 2007 Paper

Modeling visible and infrared stimulated emission from Tb3+ in TbAlO3

Kelly Nash, John Gruber, Raylon Yow, Uygun Valiev, Dhiraj Sardar

Proceedings Volume 6451, 64511A (2007) https://doi.org/10.1117/12.699348

KEYWORDS: Terbium, Absorption, Infrared radiation, Crystals, Spectroscopy, Visible radiation, Luminescence, Laser crystals, Infrared spectroscopy, Thermal modeling

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Proceedings Article | 14 February 2007 Paper

Optical characterization of gold and Er3+:Y2O3 nanoparticles for biosensor applications

Kelly Nash, Raylon Yow, Doug Dee, Guang-Yin Swanland, John Gruber, Dhiraj Sardar, Maogen Zhang, Waldemar Gorski

Proceedings Volume 6449, 64490J (2007) https://doi.org/10.1117/12.699080

KEYWORDS: Erbium, Nanoparticles, Crystals, Ions, Absorption, Luminescence, Metals, Biosensors, Particles, Scanning electron microscopy

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Proceedings Article | 7 March 2006 Paper

Optical properties of ocular tissues in the near infrared region

Dhiraj Sardar, Raylon Yow, Guang-Yin Swanland, Robert Thomas, Andrew T. C. Tsin

Proceedings Volume 6138, 613815 (2006) https://doi.org/10.1117/12.643874

KEYWORDS: Tissues, Scattering, Vitreous, Absorption, Optical properties, Anisotropy, Eye, Cornea, Tissue optics, Laser scattering

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SPIE Journal Paper | 1 September 2005 Open Access

Optical scattering, absorption, and polarization of healthy and neovascularized human retinal tissues

Dhiraj Sardar, Raylon Yow, Andrew Tsin, Ratna Sardar

JBO, Vol. 10, Issue 05, 051501, (September 2005) https://doi.org/10.1117/12.10.1117/1.2065867

KEYWORDS: Tissues, Scattering, Polarization, Absorption, Light scattering, Laser scattering, Tissue optics, Biomedical optics, Optical properties, Retina

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Proceedings Article | 1 June 2005 Paper

Modeling of Er in ceramic YAG and comparison with single-crystal YAG

Bahram Zandi, John Gruber, Dhiraj Sardar, Toomas Allik

Proceedings Volume 5792, (2005) https://doi.org/10.1117/12.602938

KEYWORDS: Ceramics, Erbium, Crystals, YAG lasers, Neodymium, Garnet, Luminescence, Er:YAG lasers, Rod lasers, Laser crystals

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Proceedings Article | 13 July 2004 Paper

Optical characterization of healthy and neovascularized human ocular tissues

Felipe Salinas, Dhiraj Sardar, Andrew Tsin

Proceedings Volume 5314, (2004) https://doi.org/10.1117/12.524166

KEYWORDS: Tissues, Scattering, Absorption, Transmittance, Light scattering, Retina, Optical properties, Collimation, Laser scattering, Anisotropy

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Proceedings Article | 13 July 2004 Paper

Mueller matrix of backscattered light of a chicken embryo

Dhiraj Sardar, Raylon Yow

Proceedings Volume 5314, (2004) https://doi.org/10.1117/12.523822

KEYWORDS: Tissues, Polarization, Collagen, Optical fibers, Tissue optics, Optical components, Optical activity, Light scattering, Diagnostics, Silicon

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Proceedings Article | 8 July 2004 Paper

Spectroscopic analysis of the Er3+ (4f11) absorption intensities in NaBi(WO4)2

Dhiraj Sardar, Charles Russell, Raylon Yow, John Gruber, Bahram Zandi, Edvard Kokanyan

Proceedings Volume 5332, (2004) https://doi.org/10.1117/12.523807

KEYWORDS: Absorption, Luminescence, Spectroscopy, Ions, Erbium, Crystals, Refraction, Signal detection, Analytical research, Quantum efficiency

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SPIE Journal Paper | 1 May 2004 Open Access

Optical characterization of bovine retinal tissues

Dhiraj Sardar, Felipe Salinas, John Perez, Andrew Tsin

JBO, Vol. 9, Issue 03, (May 2004) https://doi.org/10.1117/12.10.1117/1.1688813

KEYWORDS: Tissues, Scattering, Polarization, Light scattering, Absorption, Transmittance, Retina, Optical properties, Anisotropy, Monte Carlo methods

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Proceedings Article | 14 July 2003 Paper

Optical polarization of neovascularized human ocular tissues

Dhiraj Sardar, Andrew Tsin, Felipe Salinas, John Perez

Proceedings Volume 4951, (2003) https://doi.org/10.1117/12.477947

KEYWORDS: Tissues, Polarization, Light scattering, Retina, Optical properties, Scattering, Linear polarizers, Tissue optics, Glasses, Diagnostics

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SPIE Journal Paper | 1 October 2001 Open Access

Optical characterization of melanin

Dhiraj Sardar, Michael Mayo, Randolph Glickman

JBO, Vol. 6, Issue 04, (October 2001) https://doi.org/10.1117/12.10.1117/1.1411978

KEYWORDS: Scattering, Absorption, Particles, Transmittance, Optical properties, Monte Carlo methods, Light scattering, Anisotropy, Integrating spheres, Optical testing

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Proceedings Article | 4 May 2001 Paper

Physical and photochemical properties of ocular melanin

Randolph Glickman, James Gallas, Steven Jacques, Benjamin Rockwell, Dhiraj Sardar

Proceedings Volume 4241, (2001) https://doi.org/10.1117/12.431511

KEYWORDS: Particles, Absorption, Scattering, Light scattering, Visible radiation, Eye, Scanning tunneling microscopy, X-rays, Tissue optics, Retina

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Proceedings Article | 1 June 1991 Paper

Use of polarization to separate on-axis scattered and unscattered light in red blood cells

Dhiraj Sardar, Babak Nemati, Frederick Barrera

Proceedings Volume 1427, (1991) https://doi.org/10.1117/12.44124

KEYWORDS: Scattering, Blood, Light scattering, Laser scattering, Plasma, Sensors, Mie scattering, Laser tissue interaction, Polarization, Optical filters

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Showing 5 of 27 publications

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