Design and Construction of Optical & Coherence Tomography System Evaluation of its Operation as A diagnostic Technique

Abstract

The objective of this research is to design and construct an optical coherence tomography (OCT) system, beside the comparison of the efficiency of this system with other tomography systems, like Photoacoustic system and Raman spectrometer, to evaluate its operation. Michelson interferometer was designed; which represent the heart of the system, which consist of two mirrors, beam splitter to transmitt 50% of the incident light and reflect the other half. Three types of laser sources were used, helium neon with wavelength 632.8 nm and 4mW, diode lasers with two wavelengths (700 nm and 1550 nm), power ≤4.25mW. Performance of the constructed system was completed by receiving the interference fringes by the detector, which was connected to the display unit. Digital oscilloscope, with high mathematical functions, was used to display signal information in frequency domain. From the experiments results we noticed that Fourier transformation (FT) was the best mathematical function, which can be used with the constructed (OCT) system. Also CCD camera was used with the system to give two & three dimensional images for the studied samples. c The constructed system can be used for many purposes, for examples: measurement of the thickness and determination of optical properties for different samples. The samples studied by the constructed OCT system were: glass slides, polymer\ pyrex\ carbon coating, layers of onion and cancer skin. The results were represented in tables, figures and images. To prove the good performance of the constructed OCT system the results were compared with another results gained by a Photoacoustic system for the same samples. Beside that FT Raman spectroscopy was used also to differentiate between normal and abnormal tissue. The comparisons showed that the three tomographic systems can be used as diagnostic systems with high resolution. Also all tomographic systems have no ionizing effect compared with another tomography imaging (nuclear rays). The comparison proved that the constructed OCT system is operated efficiently and correctly.