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. 2008 Aug;25(8):2088-94.
doi: 10.1364/josaa.25.002088.

Can laser speckle flowmetry be made a quantitative tool?

Donald D Duncan  1 , Sean J Kirkpatrick
Affiliations

Can laser speckle flowmetry be made a quantitative tool?

Donald D Duncan et al. J Opt Soc Am A Opt Image Sci Vis. 2008 Aug.

Abstract

The ultimate objective of laser speckle flowmetry (and a host of specific implementations such as laser speckle contrast analysis, LASCA or LSCA; laser speckle spatial contrast analysis, LSSCA; laser speckle temporal contrast analysis, LSTCA; etc.) is to infer flow velocity from the observed speckle contrast. Despite numerous demonstrations over the past 25 years of such a qualitative relationship, no convincing quantitative relationship has been proven. One reason is a persistent mathematical error that has been propagated by a host of workers; another is a misconception about the proper autocorrelation function for ordered flow. Still another hindrance has been uncertainty in the specific relationship between decorrelation time and local flow velocity. Herein we attempt to dispel some of these errors and misconceptions with the intent of turning laser speckle flowmetry into a quantitative tool. Specifically we review the underlying theory, explore the impact of various analytic models for relating measured intensity fluctuations to scatterer motion, and address some of the practical issues associated with the measurement and subsequent data processing.

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Figures

Fig. 1
Fig. 1
(Color online) Historical result due to Fercher and Briers [1] and correction.
Fig. 2
Fig. 2
(Color online) Speckle contrast as a function of relative integration time for Lorentzian and Gaussian autocorrelation functions.
Fig. 3
Fig. 3
(Color online) Fractional uncertainty in decorrelation time due to uncertainty in proper correlation model.
Fig. 4
Fig. 4
(Color online) Sensitivity factors for two limiting correlation behaviors.
Fig. 5
Fig. 5
(Color online) Speckle contrast as a function of integration time for various intensity correlation laws.
See this image and copyright information in PMC

References

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