Accession Number : ADA193042

Title :   Methods for Correction of Refractive Errors.

Descriptive Note : Annual rept. Jan-Dec 84,

Corporate Author : PURDUE UNIV LAFAYETTE IN SCHOOL OF ELECTRICAL ENGINEERING

Personal Author(s) : Kak, A C

PDF Url : ADA193042

Report Date : 31 Dec 1984

Pagination or Media Count : 226

Abstract : The problem of cross sectional (tomographic) imaging of objects with diffracting sources is addressed. Specifically the area of investigation is the effect of multiple scattering and attenuation phenomena in diffraction imaging. The validity of either the Born or the Rytov approximations is the basic assumption behind all the inverse scattering techniques in diffraction tomography. To test these techniques when these assumptions are not satisfied, we have developed a computational procedure for the calculation of the 'true' scattered fields from a multi-component object. Using this procedure, the performance of two available diffraction reconstruction techniques is examined in the presence of multiple scattering effects. The simulation results show the superiority of the Synthetic Aperture technique. We have also studied the role of attenuation in the reconstruction techniques. To calculate the scattered fields from an object in the presence of attenuation, new computer simulation programs are developed. These codes are used in a simulation study of the effect of the attenuation parameter on the object reconstructions.

Descriptors :   *REFRACTION, *TOMOGRAPHY, ATTENUATION, COMPUTATIONS, COMPUTER PROGRAMS, COMPUTERIZED SIMULATION, CORRECTIONS, DIFFRACTION, ERRORS, IMAGES, INVERSE SCATTERING, PARAMETERS, SCATTERING, SIMULATION, X RAYS, MICROWAVES, ULTRASONIC RADIATION, FORWARD SCATTERING

Subject Categories : Acoustics
      Nuclear Physics & Elementary Particle Physics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE