Methods of Dynamic Speckle Analysis:Statistical Analysis

RICARDO ARIZAGA

Dynamic Laser Speckle and Applications

CRC Press, Taylor & Francis Goup

Lugar: Boca Raton, London, New York; Año: 2009; p. 95 - 113

Dynamic speckle patterns analysis from active materials gives us much useful information,as introduced in Chapter 2. The challenge is then to correlate that informationwith the phenomenon to be monitored.Links between the phenomenon and active objects under laser illumination startedto be made in the 1970s as many new approaches were found due to the developmentof computers and optical devices such as charge coupled devices. The metrologicaluses of dynamic speckle were then consolidated by systematic testing of all theapproaches suggested by the many applications. Measuring a biological or physicalvariable means to obtain from an illuminated object useful information based on atransduction, which allows the observer to evaluate, by processed images or numbers,the variables under control.This chapter describes numerical approaches for analyzing the dynamic specklepatterns produced by biological and nonbiological materials under laser illumination.It is possible to start analyzing a technology presented in the 1970s using one specklepattern,1 introducing the spatial contrast index as a first step to further indices or methodologiesthat adopt the time domain in their calculus. Speckle contrast with respectto time, as a first order statistical, is followed by second order statistical methodswhich are evaluated using time history speckle pattern (THSP) images, treated indetail in this chapter. Autocorrelation functions, statistical cummulants, and inertialmoment methods are also described, with some actual examples for consideration.