Journal ArticleDOI
A Double Wavelength Laser Doppler System to Investigate Skin Microcirculation
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In vitro calibration indicates that there is a constant ratio between the frequency responses at both wavelengths used, and the decrease of this ratio encountered in in vivo measurements is attributed to different depths of investigated skin microcirculation according to the incoming wavelengths.Abstract:
A new experimental laser Doppler setup has been designed to discriminate between total and superficial skin blood flow. This selectivity is based on the use of two wavelengths with different penetration depths into the skin. An argon ion and helium-neon laser are mounted on the same optical bench and are stabilized by an optical feedback loop. A single optical fiber directs the beams to the skin and collects the reflected light back to a photodetector, the signal of which is sampled and Fourier transformed to give a frequency power spectrum. Several models of light scattering by the skin are examined, and a single Lorentzian function is found to be the best fit for our experimental power spectra. Flow parameters have been thus measured for several in vitro and in vivo situations. In vitro calibration indicates that there is a constant ratio between the frequency responses at both wavelengths used. The decrease of this ratio encountered in in vivo measurements is attributed to different depths of investigated skin microcirculation according to the incoming wavelengths.read more
Citations
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Journal ArticleDOI
Laser Doppler, speckle and related techniques for blood perfusion mapping and imaging
TL;DR: This review article presents the theory and practice of these techniques using a tutorial approach and compares the relative merits of the scanning and full-field approaches to velocity map imaging and concludes with a review of reported applications ofThese techniques to blood perfusion mapping and imaging.
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Review of methodological developments in laser Doppler flowmetry
TL;DR: Laser Doppler flowmetry is a non-invasive method of measuring microcirculatory blood flow in tissue and the research done so far to overcome limitations is critically assessed.
Journal ArticleDOI
Bio-speckle phenomena and their application to the evaluation of blood flow
TL;DR: In this article, the authors reviewed the study of time-varying speckle phenomena observed in light-fields scattered from living objects and introduced methods for evaluating blood flow in the skin surface, internal organs, and ocular fundus.
Journal ArticleDOI
Evaluation of blood flow by laser speckle image sensing. Part 1.
TL;DR: A new method to visualize the microcirculation map using a dynamic laser speckle effect and the results were displayed in color graphics showing the spatial variation of the flow level in the area of interest.
Journal ArticleDOI
Principles and practice of the laser-Doppler perfusion technique
TL;DR: A guide to the limitations in application of the technique gives the user a clear indication of what can be achieved in new studies as well as possible inadequacy in some published investigations.
References
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Journal ArticleDOI
The Optics of Human Skin
R. Rox Anderson,John A. Parrish +1 more
TL;DR: An integrated review of the transfer of optical radiation into human skin is presented, aimed at developing useful models for photomedicine.
Journal ArticleDOI
Evaluation of a Laser Doppler Flowmeter for Measurement of Tissue Blood Flow
TL;DR: The study shows that the Doppler signal is formed essentially by heterodyne mixing of light beams backscattered in static structures and moving red cells.
Journal ArticleDOI
Model for laser Doppler measurements of blood flow in tissue.
Robert F. Bonner,Ralph Nossal +1 more
TL;DR: A theory is developed which relates quasi-elastic light scattering measurements to blood flow in tissue micro-vasculature and implies that the time decay of the photon autocorrelation function scales proportionally with cell size and inversely with mean translational speed.