Some Effects of Temporal Coherence on the First Order Statistics of Speckle
TL;DR: In this article, the first order probability density function of the intensity in a speckle pattern is considered as a function of spectral bandwidth of the incident light, and it is shown that the sta...
Abstract: Moments and the first order probability density function of the intensity in a speckle pattern are considered as a function of the spectral bandwidth of the incident light. It is shown that the sta...
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TL;DR: It is shown that partially coherent light can be used to determine material parameters for highly scattering media and measured data for stratified materials with differing scattering properties indicate that this technique may be useful in detecting inhomogeneities.
Abstract: The statistical properties of laser speckle with partially coherent light are related to the scattering characteristics of an optically diffuse material. A diffusion equation model is shown to yield a speckle contrast ratio that agrees well with measurements of opaque plastics of varying thicknesses. We show that partially coherent light can be used to determine material parameters for highly scattering media. Measured data for stratified materials with differing scattering properties indicate that this technique may be useful in detecting inhomogeneities.
144 citations
TL;DR: The statistical properties of a speckle pattern depend, in general, on both the coherence of the incident light and the statistics of the scattering surface or medium as discussed by the authors, and it was found that the value of the r.m.s. height variation of a scattering surface strongly influenced the statistical properties, even for surfaces with a Gaussian distribution of surface heights.
Abstract: Publisher Summary This chapter discusses the statistics of speckle patterns. The statistical properties of a speckle pattern depend, in general, on both the coherence of the incident light and the statistics of the scattering surface or medium. In a large number of practical situations normal speckle patterns are produced; the statistics of these speckle patterns are well-established both theoretically and experimentally, and in particular, they do not depend on the detailed scattering properties of the scattering medium. When examining the effects of polychromatic illumination on speckle statistics, it was found that the value of the r.m.s. height variation of a scattering surface strongly influenced the statistical properties of the scattered intensity. In addition, the chapter shows that the general relationship between the scattered intensity and the scattering surface may be very complicated, even for surfaces with a Gaussian distribution of surface heights.
136 citations
TL;DR: In this paper, a method for the detection and localization of inhomogeneities embedded within highly scattering media that employs speckle statistics with a partially coherent light source is presented.
Abstract: We present a method for the detection and localization of inhomogeneities embedded within highly scattering media that employs speckle statistics with a partially coherent light source. Variations in speckle contrast as a function of position are used to interrogate inhomogeneities deeply embedded within scattering media. A numerical model based on photon diffusion theory is introduced to predict speckle contrast as a function of scan position. This model uses measured speckle data to determine scattering and absorption parameters.
123 citations
TL;DR: In this article, the relations between surface statistics and the near and far-field scattered light statistics are surveyed, mainly using scalar diffraction theory, and the methods which have been proposed and used are grouped and described according to whether they operate in the near or the far field and whether they use monochromatic or polychromatic light.
Abstract: The relations between surface statistics and the near- and far-field scattered light statistics are surveyed, mainly using scalar diffraction theory. The methods which have been proposed and used are grouped and described according to whether they operate in the near-field or the far-field and whether they use monochromatic or polychromatic light. Several methods emerge as promising for practical application to non-contacting and non-destructive testing.
122 citations
TL;DR: Ultrasound-modulated optical tomography based on the measurement of laser-speckle contrast was investigated and the contrast of the speckle pattern formed by the transmitted light was found to depend on the ultrasonic modulation and could be used for imaging.
Abstract: Ultrasound-modulated optical tomography based on the measurement of laser-speckle contrast was investigated. An ultrasonic beam was focused into a biological-tissue sample to modulate the laser light passing through the ultrasonic column inside the tissue. The contrast of the speckle pattern formed by the transmitted light was found to depend on the ultrasonic modulation and could be used for imaging. Variation in the speckle contrast reflected optical inhomogeneity in the tissue. With this technique, two-dimensional images of biological-tissue samples of as much as 25 mm thick were successfully obtained with a low-power laser. The technique was experimentally compared with speckle-contrast-based, purely optical imaging and with parallel-detection imaging techniques, and the advantages over each were demonstrated.
116 citations
References
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Book•
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01 Jan 1959
TL;DR: In this paper, the authors discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals, including interference, interferometers, and diffraction.
Abstract: The book is comprised of 15 chapters that discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals. The text covers the elements of the theories of interference, interferometers, and diffraction. The book tackles several behaviors of light, including its diffraction when exposed to ultrasonic waves.
19,815 citations
[...]
01 Oct 1999
TL;DR: In this article, the authors discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals, including interference, interferometers, and diffraction.
Abstract: The book is comprised of 15 chapters that discuss various topics about optics, such as geometrical theories, image forming instruments, and optics of metals and crystals. The text covers the elements of the theories of interference, interferometers, and diffraction. The book tackles several behaviors of light, including its diffraction when exposed to ultrasonic waves.
19,503 citations
TL;DR: A general theorem is provided for the moments of a complex Gaussian video process that states that an n th order central product moment is zero if n is odd and is equal to a sum of products of covariances when n is even.
Abstract: A general theorem is provided for the moments of a complex Gaussian video process. This theorem is analogous to the well-known property of the multivariate normal distribution for real variables, which states that an n th order central product moment is zero if n is odd and is equal to a sum of products of covariances when n is even.
411 citations
01 Sep 1959
TL;DR: In this article, the probability distribution p(n, T) of the number of counts n from a photoelectric detector illuminated by coherent light for a time T is studied, by associating photons stochastically with Gaussian random waves.
Abstract: The probability distribution p(n, T) of the number of counts n from a photoelectric detector illuminated by coherent light for a time T is studied, by associating photons stochastically with Gaussian random waves. The cumulants of the distribution are derived and it is shown to be of the expected form for a boson assembly in a limited volume of phase space. The distribution depends strongly on the degeneracy of the light beam. It approaches the Poisson form for classical particles at low degeneracies and the distribution characteristic of classical waves at high degeneracies. The analysis leads, incidentally, to an expression for the extent of the unit cell of phase space in the direction of the beam. It is argued that this should be adopted as the measure of coherence length.
386 citations
01 Nov 1965
TL;DR: In this paper, the statistical performance of pulsed optical radars that use energy detection is considered, and the physical factors influencing the number of observed correlation cells for the cases of partial and total interception of the transmitted beam are examined.
Abstract: The statistical performance of pulsed optical radars that use energy detection is considered. While the signal photoelectron statistics produced by a return from a specular target are Poisson, those produced by a return from a rough target are shown to be negative binomial. Radar performance is shown to depend on the number of spatial correlation cells of energy density observed by the receiving aperture, with performance generally deteriorating as the number of observed cells decreases. The physical factors influencing the number of observed correlation cells for the cases of partial and total interception of the transmitted beam are examined.
288 citations