Acousto-optics in scattering media: an analytical model for anisotropic scattering

We have calculated analytically the temporal autocorrelation function of the electric field component of multiply scattered coherent light transmitted through an anisotropically scattering medium and irradiated with a plane ultrasonic wave. The accuracy of the analytical solution is verified with an independent Monte Carlo simulation. The analytical model shows that an approximate similarity relation exists

Correlation Transfer and Diffusion of Ultrasound-Modulated Multiply Scattered Light

We develop a temporal correlation transfer equation (CTE) and a temporal correlation diffusion equation (CDE) for ultrasound-modulated multiply scattered light. These equations can be applied to an optically scattering medium with embedded optically scattering and absorbing objects to calculate the power spectrum of light modulated by a nonuniform ultrasound field. We present an analytical solution based on the CDE and Monte Carlo simulation results for light modulated by a cylinder of ultrasound in an optically scattering slab. We further validate with experimental measurements the numerical calculations for an actual ultrasound field. The CTE and CDE are valid for moderate ultrasound pressures and on a length scale comparable with the optical transport mean-free path. These equations should be applicable to a wide spectrum of conditions for ultrasound-modulated optical tomography of soft biological tissues

Correlation transfer equation for ultrasound-modulated multiply scattered light

In this paper, we develop a temporal correlation transfer equation (CTE) for ultrasound-modulated multiply scattered light. The equation can be used to obtain the time-varying specific intensity of light produced by a nonuniform ultrasound field in optically scattering media that have a heterogeneous distribution of optical parameters. We also develop a Monte Carlo algorithm that can provide the spatial distribution of the optical power spectrum in optically scattering media with focused ultrasound fields, and heterogeneous distributions of optically scattering and absorbing objects. Derivation of the CTE is based on the ladder diagram approximation of the Bethe-Salpeter equation that assumes moderate ultrasound pressures. We expect the CTE to be applicable to a wide spectrum of conditions in the ultrasound-modulated optical tomography of soft biological tissues

Correlation transfer equation for multiply scattered light modulated by an ultrasonic pulse: an analytical model and Monte Carlo simulation

We present derivation of the temporal correlation transfer equation (CTE) for multiply scattered light modulated by an ultrasound pulse. The equation can be used to obtain the time-varying specific intensity of light produced by a pulsed and nonuniform ultrasound field in optically scattering media that have a heterogeneous distribution of optical parameters. We also develop a Monte Carlo algorithm that can simulate the spatial distribution of the time-dependent power spectrum density of light modulated by a focused ultrasound pulse in optically scattering media with heterogeneous distributions of optically scattering and absorbing objects. Derivation is based on the ladder diagram approximation of the Bethe-Salpeter equation that assumes moderate ultrasound pressures. We expect these results to be applicable to a wide spectrum of conditions in the ultrasound-modulated optical tomography of soft biological tissues

Correlation transfer equation for multiply scattered light modulated by an ultrasonic pulse

We develop a temporal correlation transfer equation (CTE) and a Monte Carlo algorithm (MC) for multiply scattered light modulated by an ultrasonic pulse propagating in an optically scattering medium, where the ultrasound field can be nonuniform and the medium can have spatially heterogeneous distribution of optical parameters. The CTE and MC can be used to obtain the time-varying specific intensity and the spatial distribution of the time-dependent power spectral density, respectively, of ultrasound-modulated light. We expect the CTE and MC to be applicable for estimation of contrast and resolution in a wide spectrum of conditions in ultrasound-modulated optical tomography of soft biological tissues

Development of the correlation transfer equation of ultrasound-modulated multiply scattered light: a diagrammatic approach

In this paper, we develop a temporal correlation transfer equation (CTE) for ultrasound-modulated multiply scattered light. The equation can be used to obtain the temporal frequency spectrum of the optical intensity produced by a nonuniform ultrasound field in optically scattering media. Derivation of the CTE is based on the ladder diagram approximation of the Bethe-Salpeter equation. We expect the CTE to be applicable to a wide spectrum of conditions in the ultrasound-modulated optical tomography of soft biological tissues

Modulation of multiply scattered coherent light by ultrasonic pulses: An analytical model

We present an analytical solution for the acousto-optical modulation of multiply scattered light in a medium irradiated with a train of ultrasound pulses. Previous theory is extended to cases where the ultrasound-induced optical phase increments between the different scattering events are strongly correlated, and it is shown that the approximate similarity relation still holds. The relation between the ultrasound induced motions of the background fluid and the optical scatterers is generalized, and it is shown that correlation exists between the optical phase increments that are due to the scatterer movement and the optical phase increments that are due to the modulation of the optical index of refraction. Finally, it is shown that compared with the spectrum of ultrasound pulses, the power spectral density of acousto-optically modulated light is strongly attenuated at the higher ultrasound frequencies