OPTICAL COHERENCE TOMOGRAPHY (OCT) IMAGING IS A HIGH RESOLUTION AND NON-INVASIVE IMAGING MODALITY THAT PROVIDES CROSS-SECTIONAL IMAGES OF A TISSUE. THE TIME OF FLY IN THE SIGNAL PROCESSING OF THE OCT SYSTEM IS CALCULATED BASED ON A CONSTANT REFRACTIVE INDEX. DIFFERENT LAYERS OF THE COMPLEX TISSUES HOWEVER HAVE DIFFERENT REFRACTIVE INDICES. THIS ISSUE PROMPTS PIXELS IN THE IMAGE TO BE MISPLACED AND THAT MAKES IT DIFFICULT FOR THE PHYSICIANS TO HAVE AN ACCURATE DIAGNOSIS OF ABNORMALITIES BASED ON OCT IMAGING. IN THIS PAPER, WE PROPOSE A NOVEL POST-PROCESSING METHOD TO CORRECT FOR THE REFRACTIVE INDEX. THE PROPOSED METHOD IS BASED ON IMAGING A TISSUE TO WHICH A NEEDLE HAS PENETRATED.

INTRODUCTION: MUCH EXPERIMENTAL AND THEORETICAL EFFORTS HAS BEEN RECENTLY DEVOTED TO THE STUDY OF A NEW TYPE OF METAMATERIALS THAT HAVE SIMULTANEOUSLY NEGATIVE ELECTRIC PERMITTIVITY Ε AND MAGNETIC PERMEABILITY ΜAND ARE THUS TERMED AS NEGATIVE REFRACTIVE-INDEX MATERIALS (NIM), OR LEFT-HANDED MATERIALS [1]. OVER THIRTY YEARS AGO, VESELAGO [2] PREDICTED THEORETICALLY THAT ELECTROMAGNETIC WAVES PROPAGATING IN ISOTROPIC NIM’S POSSESS SEVERAL PECULIAR CHARACTERISTICS, INCLUDING ANOMALOUS REFRACTION, REVERSAL OF BOTH THE DOPPLER SHIFT AND THE CERENKOV RADIATION, AND REVERSAL OF RADIATION PRESSURE TO RADIATION TENSION [3]. ON THE OTHER HAND, SCATTERING AND ABSORPTION OF LIGHT BY NANOSTRUCTURES IS ONE OF THE PHYSICISTS & CHEMISTS MOTIVATIONS.MIE COULD PROPOSE EXACT SOLUTION FOR LIGHT SCATTERING OF SPHERICAL NANOPARTICLES BY SOLVING OF MAXWELL'S EQUATIONS IN 1908 [3].MIE'S THEORY WAS REPRESENTED FOR ISOTROPIC, HOMOGENEOUS AND SPHERICAL PARTICLES INTOISOTROPIC, HOMOGENEOUS AND NON-ABSORBING SURROUNDING MEDIUMS [4].IN THIS WORK, WE SUGGEST THAT FOR SPECIAL WAVELENGTH AND NANOHOLES SIZE, THE EFFECTIVE REFRACTIVE INDEX SHOWS NEGATIVE VALUE IN MIE'S THEORY AND HENCE IT COULD BE CONSIDERED AS META-MATERIALS.

RECENTLY, MUCH ATTENTION HAS BEENDEVOTED TO HIGH REFRACTIVE INDEX (HIGH-N) POLYMERS FOR THEIR PRACTICAL APPLICATIONS INADVANCED OPTOELECTRONIC FABRICATIONS [1]. ACCORDING TO THE LORENTZ–LORENZ EQUATION, THEREFRACTIVE INDICES OF CONVENTIONAL POLYMERS CAN BEINCREASED BY THE INTRODUCTION OF SUBSTITUENTS WITH HIGH MOLAR REFRACTIONS, LOW MOLARVOLUMES, OR HIGH DENSITY [2]. AMONG THE VARIOUS SUBSTITUENTS, SULFUR-CONTAINING GROUPS SEEMTO BE THE MOST OPTIMAL CANDIDATES BECAUSE OFTHEIR HIGH STABILITY AND POLARIZABILITY TO DEVELOP HIGH-N POLYMERS [3]. IN ADDITION, TO ENHANCETHE REFRACTIVE INDICES OF POLYMERS WHILE MAINTAINING HIGH OPTICAL TRANSPARENCY, INTRODUCTION OF HETEROAROMATIC RINGS CONTAINING–C=N– BONDING WOULD BE AN EFFECTIVE METHOD [4].IT WAS FOUND THAT THEINCORPORATION OF BOTH HIGHLY POLARIZABLE THIAZOLERINGS HAVING C=N BONDS AS WELL AS FLEXIBLE THIOETHER LINKAGES RESULTED IN POLYMERS WITH HIGH REFRACTIVE INDICES, LOW BIREFRINGENCE’S, AND RELATIVELY GOOD OPTICAL TRANSPARENCY [5].IN THIS STUDY, A SERIES OF NEW POLYAMIDES (PAS) BEARING THIOETHER LINKAGES AND HETEROAROMATICTHIAZOLE RINGS WERE PREPARED FROM A NOVEL THIOETHER-BRIDGED DIAMINE MONOMER (DA) AND DIFFERENT AROMATIC DICARBOXYLIC ACIDS (1-5) USING A DIRECT POLYCONDENSATION PROCEDURE. THE RESULTINGPOLYMERS WERE OBTAINED IN HIGH YIELDS AND POSSESSED HIGH INHERENT VISCOSITIES. ALL OF THE POLYMERS WERE AMORPHOUS IN NATURE, SHOWED GOOD SOLUBILITY AND COULD BE EASILY DISSOLVED IN AMIDE-TYPEPOLAR APROTIC SOLVENTS AND EVEN DISSOLVED IN LESS POLAR SOLVENTS. THEY EXHIBITED EXCELLENT THERMAL STABILITY WITH GLASS TRANSITION TEMPERATURES BETWEEN 207–239°C AND 10% WEIGHT LOSS TEMPERATURES IN EXCESS OF 424OC IN NITROGEN AND 469 °C IN AIR ATMOSPHERE. THE OPTICAL TRANSMITTANCES OF THE PA FILMS AT 450 NM WERE HIGHER THAN 85%. THE COMBINATION OF THETHIAZOLE RINGS AND THIOETHER LINKAGES PROVIDED PAS WITH HIGH AVERAGE REFRACTIVE INDICES OF 1.7414-1.7542 AND LOW BRIEFRINGENCES OF 0.0061–0.0087 AT 632.8 NM.