191 research outputs found
Beta measurements
The second year's results of the BETA project research are presented. The program is divided into two areas, aerosol modification and climatology in the trade wind region and the climatology of BETA (CO2) on remote mountain top locations. Limited data is available on the aerosol climatology of the marine free troposphere (MFT) in the trade wind region. In order to study the effects of cumulus convection on the MFT values of BETA, a cloud model was developed to simulate the evolution of a typical Pacific trade wind cumulus cloud. The stages involved in this development are outlined. The assembly of the major optical components of the lidar was made. Tests were run of the spectral bandwidth of the Synrad laser when a portion of the beam is mixed with a component which has traveled 450 meters corresponding to a delay of 1.5 microsecs. The bandwidth of the beat signal was measured to be 3 KHz. The data processing system based on a parallel processing filter bank analyzer using true time squaring detectors at each filter was completed
Multiple Projection Optical Diffusion Tomography with Plane Wave Illumination
We describe a new data collection scheme for optical diffusion tomography in
which plane wave illumination is combined with multiple projections in the slab
imaging geometry. Multiple projection measurements are performed by rotating
the slab around the sample. The advantage of the proposed method is that the
measured data can be much more easily fitted into the dynamic range of most
commonly used detectors. At the same time, multiple projections improve image
quality by mutually interchanging the depth and transverse directions, and the
scanned (detection) and integrated (illumination) surfaces. Inversion methods
are derived for image reconstructions with extremely large data sets. Numerical
simulations are performed for fixed and rotated slabs
Single-Scattering Optical Tomography: Simultaneous Reconstruction of Scattering and Absorption
We demonstrate that simultaneous reconstruction of scattering and absorption
of a mesoscopic system using angularly-resolved measurements of scattered light
intensity is possible. Image reconstruction is realized based on the algebraic
inversion of a generalized Radon transform relating the scattering and
absorption coefficients of the medium to the measured light intensity and
derived using the single-scattering approximation to the radiative transport
equation.Comment: This is a sequel to physics/070311
On the Convergence of the Born Series in Optical Tomography with Diffuse Light
We provide a simple sufficient condition for convergence of Born series in
the forward problem of optical diffusion tomography. The condition does not
depend on the shape or spatial extent of the inhomogeneity but only on its
amplitude.Comment: 23 pages, 7 figures, submitted to Inverse Problem
Photoacoustic effect for multiply scattered light
We consider the photoacoustic effect for multiply scattered light in a random medium. Within the accuracy of the diffusion approximation to the radiative transport equation, we present a general analysis of the sensitivity of a photoacoustic wave to the presence of one or more small absorbing objects. Applications to tumor detection by photoacoustic imaging are suggested
Optical Tomography on Graphs
We present an algorithm for solving inverse problems on graphs analogous to those arising in diffuse optical tomography for continuous media. In particular, we formulate and analyze a discrete version of the inverse Born series, proving estimates characterizing the domain of convergence, approximation errors, and stability of our approach. We also present a modification which allows additional information on the structure of the potential to be incorporated, facilitating recovery for a broader class of problems
Optical Tomography on Graphs
We present an algorithm for solving inverse problems on graphs analogous to those arising in diffuse optical tomography for continuous media. In particular, we formulate and analyze a discrete version of the inverse Born series, proving estimates characterizing the domain of convergence, approximation errors, and stability of our approach. We also present a modification which allows additional information on the structure of the potential to be incorporated, facilitating recovery for a broader class of problems
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