SISTEM TOMOGRAFI OPTIS SINAR TERUSAN TRANSMITTED LIGHT OPTICAL TOMOGRAPHY SYSTEM

Abstract

We conducted theoretical, simulation and simplified experimental studies on Transmitted Light Optical Tomography (TLT) system. TLT was a concept in which light was used as a tracer with objects examined including materials which might interact optically. The studies were conducted in order to ascertain the foundation of TLT concept for possibly examining internal structures of a transparent body. Theoretical study aimed to identify the analytical physics quantity being able to represent optical properties of a transparent body as the internal structure of the body being examined. By studying both Maxwell equations on the interaction of a transparent isotropic body with light and Poynting vector concept, we found Beer-Lambert formulae. Then, by involving Fresnel law, we could use the formulae as the foundation of setting the fundamental variables in tomography, namely, raysum and projection. Results of the theoretical study showed that TLT images represented physics quantity, namely, imaginary refractive index. Simulation study aimed to examine the validity of the formulae in the case of virtual engineering system before constructing its real system. Hence, we developed a simulator to examine 2D numerical matrics object representing imaginary refractive index. In the simulator, light was passed through the object so that physics quantity within the object interacted with the light according to Beer-Lambert, Fresnel and Snellius laws. The simulator executed the tomography aquisition processes of ray-sum and projection by complying the assumption of paralel light beam. The projections from various angles were set in a sinogram form and then to be reconstructed to provide TLT image. Results of simulation study showed that the tomography images were structurally in accordance with their numerical shapes, but imaginary refractive index of the images still systematically deviated from their numerical values. Experimental study aimed to examine TLT concept in laboratory. Hence, we chose optical materials representing amorf materials, which were transparent of light (3800Ao-7400Ao) and had electrical conductivity ranging from 3.10-15 mho.m-1 to 86,065 mho.m-1, and for experimental purpose, we found an experimental object with components including air, glass and crude palm oil. Results of the experiment acquired with the developed TLT system showed that object structure of the reconstruction images was in accordance with that of the expected shapes, but we had yet to validate their imaginary refractive index