Mr. Hansford C. Hendargo Profile

Hansford C. Hendargo

Graduate Student at Duke Univ

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Author

Publications (5)

Proceedings Article | 1 February 2012 Paper

Dual-depth SSOCT for simultaneous complex resolved anterior segment and conventional retinal imaging

Al-Hafeez Dhalla, Theresa Bustamante, Derek Nanikivil, Hansford Hendargo, Ryan McNabb, Anthony Kuo, Joseph Izatt

Proceedings Volume 8213, 82131G (2012) https://doi.org/10.1117/12.911306

KEYWORDS: Image segmentation, Polarization, Optical coherence tomography, Imaging systems, Retina, Heterodyning, Coherence (optics), Computer programming, Eye, Retinal scanning

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Proceedings Article | 16 February 2011 Paper

Doppler velocity detection limitations in spectrometer and swept-source Fourier-domain optical coherence tomography

Hansford Hendargo, Ryan McNabb, Al-Hafeez Dhalla, Neal Shepherd, Joseph Izatt

Proceedings Volume 7889, 788911 (2011) https://doi.org/10.1117/12.876013

KEYWORDS: Spectroscopy, Optical coherence tomography, Doppler effect, Doppler tomography, Data acquisition, Signal to noise ratio, Velocity measurements, Signal attenuation, Imaging systems, Data centers

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Proceedings Article | 20 February 2009 Paper

Synthetic wavelength-based phase unwrapping in Fourier domain optical coherence tomography

Hansford Hendargo, Mingtao Zhao, Neal Shepherd, Joseph Izatt

Proceedings Volume 7168, 71681C (2009) https://doi.org/10.1117/12.808077

KEYWORDS: Optical coherence tomography, Microscopy, Doppler tomography, Phase interferometry, Phase measurement, Signal to noise ratio, Refractive index, Spectroscopy, Coherence (optics), Polarization

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Phase-sensitive adjuncts to optical coherence tomography (OCT) including Doppler and polarization-sensitive implementations allow for quantitative depth-resolved measurements of sample structure and dynamics including fluid flows and orientation of birefringent structures. The development of Fourier-domain OCT (FDOCT), particularly spectrometer-based spectral-domain systems with no moving parts (spectral-domain OCT or SDOCT), have greatly enhanced the phase stability of OCT systems particularly when implemented in a common-path geometry. The latter combination has given rise to a new class of nm-scale sensitive quantitative phase microscopies we have termed spectral domain phase microscopy. However, the phase information in all of these techniques suffers from a 2π ambiguity that limits resolvable pathlength differences to less than half the source center wavelength. This is problematic for situations such as cellular imaging, Doppler velocimetry, or polarization sensitive applications where it may be necessary to monitor sample profiles, displacements, phase differences, or refractive index variations which vary rapidly in space or time. A technique previously introduced in phase shifting interferometry uses phase information from multiple wavelengths to overcome this limitation. We show that by appropriate spectral windowing of the broadband light source already used in OCT, particularly by reshaping the source spectrum about two different center wavelengths, the resulting phase variation may be cast in terms of a much longer synthetic wavelength chosen to span the phase variation of interest. We show theoretically that the optimal choice of synthetic wavelength depends upon a tradeoff between the minimum resolvable phase and the length of unambiguous phase measurement. We demonstrate this technique using a broadband source centered at 790 nm by correctly reconstructing the phase profile from a phantom sample containing multiple 2π wrapping artifacts at the center wavelength and compare our result with atomic force microscopy.

Proceedings Article | 12 February 2009 Paper

Combined hyperspectral and spectral domain optical coherence tomography microscope for non-invasive hemodynamic imaging

Melissa Skala, Hansford Hendargo, Andrew Fontanella, Mark Dewhirst, Joseph Izatt

Proceedings Volume 7174, 71740I (2009) https://doi.org/10.1117/12.808183

KEYWORDS: Tumors, Optical coherence tomography, Blood circulation, Blood, Oxygen, Speckle, Doppler effect, Microscopes, Hemodynamics, Hyperspectral imaging

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Proceedings Article | 12 February 2008 Paper

Extension of spectral domain phase microscopy to three-dimensional nanoscale displacement mapping in cardiomyocytes

Audrey Ellerbee, Hansford Hendargo, Amy Motomura, Joseph Izatt

Proceedings Volume 6861, 686108 (2008) https://doi.org/10.1117/12.765239

KEYWORDS: Optical coherence tomography, Microscopy, Data acquisition, Interferometry, Image processing, Digital holography, Motion measurement, 3D acquisition, Heart, 3D image processing

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