A Conceptual Modeling Of Optical Properties Of Ruby Stone Using Charge-Coupled Device (CCD) Tomography Approach

Malaysia is one of the countries that imports rubies from Myanmar for various uses in the manufacturing industries, precious stone industries, dentistry, and medical applications. Previous tools for determining the gradation of ruby stones are based on the assessment by human eyes and require a lot of experience. In this study, the research presented a conceptual model of optical properties of ruby stones using the CCD Tomography technique. The transparency and clarity of the ruby stones are some of the important attributes that are evaluated in the study. The first objective of this present study was to examine the optical properties of ruby stones using charge-coupled device (CCD) tomography. The second objective was to investigate and identify the light intensities of various grades of ruby stones using CCD tomography and Laboratory Virtual Instrument Engineering Workbench (LabVIEW) programming software as classified commercially by the Gemmological Institute of America (GIA) database. The third objective was to validate the optical properties of the ruby stones by comparing the simulation output images to that of the experimental output images. Here, the research presented a standardized conceptual model for the optical properties of the ruby stones using the CCD Tomography technique. A Linear Back Projection (LBP) algorithm was used for reconstructing the 3D images of the ruby stones based on the Refractive Index (RI) values of 1.762 and 1.770. The algorithm was programmed using the LabVIEW programming software tools. These image reconstructions assisted in
analysing the transparency of the ruby stones after the 2-sample t-test, which were necessary for evaluating and grading the stone quality. Apart from that, two types of CCD tomography image reconstruction systems, with and without the use of a laser as the light source, were analysed to investigate the best conceptual modeling with which to evaluate the optical properties of ruby stones. The study suggested that the image reconstruction system with laser as the light source or transmitter was efficient in differentiating between the 2 different RI values of the ruby stones. The result also concluded that the relative error value between the theoretical and experimental value of this system is 10.15% which has successfully proved the capability of CCD tomography system in evaluating the optical properties of ruby stone based on its clarity.