History of Laser-Doppler Blood Flowmetry

Shepherd, A. P.

doi:10.1007/978-1-4757-2083-9_1

Cited by 98 publications

(132 citation statements)

References 21 publications

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“…This processor was further modified [26,27] and was widely accepted by researchers and manufacturers. A detailed review of early technical innovations (till 1990) in laser Doppler flowmetry can be found in [10]. Laser Doppler perfusion monitoring (LDPM), which is a one-point measurement technique, was then extended to produce a perfusion map of an area of tissue by stepwise scanning of the laser beam over the tissue surface, called laser Doppler perfusion imaging (LDPI).…”

Section: Technical Innovations and Introduction Of New Methods Based mentioning

confidence: 99%

“…In order to estimate the perfusion from the Doppler broadened photodetector signal, several frequency-weighted signal-processing algorithms were developed [10]. Koelink et al [30] developed a digital signal-processing method and compared this with the performance of analog signalprocessing methods.…”

Section: Signal Processing In Laser Doppler Flowmetrymentioning

confidence: 99%

“…Early developments in laser Doppler flowmetry and its clinical applications were reviewed by Shepherd and Öberg [10]. Obeid et al [12] reviewed the limitations of the technique.…”

Section: Introductionmentioning

confidence: 99%

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Review of methodological developments in laser Doppler flowmetry

et al. 2008

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Section: Technical Innovations and Introduction Of New Methods Based mentioning

confidence: 99%

Section: Signal Processing In Laser Doppler Flowmetrymentioning

confidence: 99%

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Review of methodological developments in laser Doppler flowmetry

et al. 2008

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“…The fundamental principles of LDF applied to the measurement of SkBF have been described in detail in several publications (Serup et al, 2006;Shepherd & Oberg, 1990). …”

Section: Principles Of Laser Doppler Flowmetrymentioning

confidence: 99%

Assessment of Human Skin Microcirculation and Its Endothelial Function Using Laser Doppler Flowmetry

Lenasi¹

2011

Medical Imaging

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“…6 This will enable path length resolved measurements in mixed media such as tissue perfused with blood. 7 Since the use of single mode fibers does lead to a too low signal level in a dual fiber geometry as used in laser Doppler techniques, we take the advantage of multimode fibers to collect sufficient scattered light at large fiber distances. The aim of the present work is to establish the performance of the system in terms of its resolution of optical path length assessment and its ability to represent various flow speeds within the physiological velocity range.…”

mentioning

confidence: 99%

Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurements of diffuse light

Varghese

Rajan

Leeuwen

et al. 2007

Review of Scientific Instruments

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The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a turbid suspension of particles undergoing Brownian and translational motion. The path length resolution of this instrument is compared with a system using single mode fibers for illumination and detection. The optical path lengths are determined from the zero order moment of the phase modulation peak in the power spectrum. The weighted first moment, which is equal to the average Doppler shift, shows a linear response for different mean flow velocities within the physiological range. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2823558͔ Path length resolved temporal fluctuations of photon intensity and the corresponding Doppler shift in dynamic media can be measured using low coherence interferometry. [1][2][3][4][5] Path length distributions in static and mixed static-dynamic media can be measured by phase modulated low coherence Mach-Zehnder interferometer. 6 This will enable path length resolved measurements in mixed media such as tissue perfused with blood. 7 Since the use of single mode fibers does lead to a too low signal level in a dual fiber geometry as used in laser Doppler techniques, we take the advantage of multimode fibers to collect sufficient scattered light at large fiber distances. The aim of the present work is to establish the performance of the system in terms of its resolution of optical path length assessment and its ability to represent various flow speeds within the physiological velocity range. In previous reports, 1-6 coherence gated optical Doppler measurements are performed on nonflowing samples, in which the Doppler shift was imparted due to Brownian motion of particles.A broadband superluminescent diode ͑Inject LM2-850, = 832 nm, ⌬ FWHM = 17 nm, coherence length L C =18 m͒ that yields 2 mW of power from the single mode pigtail fiber is used as the light source. In contrast to single mode fiber optic interferometers used for path length resolved measurements, 1-3 adopting on axis back reflection and confocal detection of singly scattered photons, our system uses multimode graded index fibers ͓core diameter= 100 m, numerical aperture ͑NA͒ = 0.29, length= 1 m͔ for detection of multiply scattered light, with positions for illumination ͑single mode fibers, mode field diameter= 5.3 m, NA = 0.14͒ and detection separated by a distance of 300 m. This spatial separation corresponds to five times the scattering mean-free-path length in an aqueous suspension of 10% of Intralipid 20 ͑ s Ј= 5.0 mm −1 , a = 0.001 mm −1 , g = 0.637͒ that we used in this study. For measuring the path length resolution of single mode fiber optic interferometer, single mode fibers are used for detection. The coherence length of the light source, and the intermodal dispersion in the detection fiber, define the path l...

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History of Laser-Doppler Blood Flowmetry

Cited by 98 publications

References 21 publications

Review of methodological developments in laser Doppler flowmetry

Review of methodological developments in laser Doppler flowmetry

Assessment of Human Skin Microcirculation and Its Endothelial Function Using Laser Doppler Flowmetry

Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurements of diffuse light

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