Optical Tomography for Media with Variable Index of Refraction

Optical tomography is the use of near-infrared light to determine the optical absorption and scattering properties of a medium M ⊂ Rn. If the refractive index is constant throughout the medium, the steady-state case is modeled by the stationary linear transport equation in terms of the Euclidean metric and photons which do not get absorbed or scatter travel along straight lines. In this expository article we consider the case of variable refractive index where the dynamics are modeled by writing the transport equation in terms of a Riemannian metric; in the absence of interaction, photons follow the geodesics of this metric. The data one has is the measurement of the out-going flux of photons leaving the body at the boundary. This may be knowledge of both the locations and directions of the exiting photons (fully angularly resolved measurements) or some kind of average over direction (angularly averaged measurements). We discuss the results known for both types of measurements in all spatial dimensions

Stability of the Gauge Equivalent Classes in Inverse Stationary Transport in Refractive Media

In the inverse stationary transport problem through anisotropic attenuating, scattering, and refractive media, the albedo operator stably determines the gauge equivalent class of the attenuation and scattering coefficients

Total Determination of Material Parameters from Electromagnetic Boundary Information

In this paper we complete the proof that the material parameters can be obtained for a chiral electromagnetic body from the boundary admittance map. We prove that from the admittance map, the parameters are uniquely determined to infinite order at the boundary. This removes the assumption of such knowledge in the result of the second author regarding interior determination for chiral media