A PATTERN-DEVIATION SCANNER FOR PRECISE MEASUREMENT OF INTERNAL COMPONENT LOCATIONS

RESEARCHERS ARE INVESTIGATING THE FEASIBILITY OF MEASURING TO VERY HIGH RESOLUTION THE LOCATIONS OF MULTIPLE COMPONENTS OF KNOWN COMPOSITION WHOSE POSTITIONS ARE INTENDED TO CONFORM TO A WELL-DEFINED PATTERN INSIDE A STRUCTURE. THE TECHNIQUE DEPENDS ON SCANNING PHOTON BEAMS ACROSS THE STRUCTURE SURFACE, DETECTING TRANSMITTED AND SCATTERED RADIATION IN COLLIMATED DETECTORS, AND EMPLOYING TECHNIQUES SUCH AS TEMPLATE-MATCHING THAT INCORPORATE A PRIORI INFORMATION SUCH AS THE SSIZE AND COMPOSITION OF THE COMPONENTS AND THEIR INTENDED PATTERN. TRADITIONAL TOMOGRAPHY IS NOT ADQUATE BECAUSE IT IS INCAPABLE OF SUCH HIGH SPATIAL RESOLUTION. RESEARCHERS ARE EMPLOYING A COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION TO STUDY DESIGN ISSUES SUCH AS SOURCE ENERGY, SOURCE AND DETECTOR COLLIMATION, SCAN MODE (TRANSLATIONAL, ROTATIONAL, OR BOTH), SCAN STEP SIZE AND SPEED, AND REQUIRED NUMBER OF DETECTORS AND THEIR LOCATIONS FOR A PRACTICAL INSTRUMENT. KEY FEATURES INCLUDE RIGOROUS MODELING OF THE PHOTON TRANSPORT PROCESS, INCLUSION OF TEMPLATE-MATCHING AND PATTERN-RECOGNITION ALGORITHMS, AND CONSIDERATION OF AN INTERATIVE PROCESS TO IDENTIFY MISALIGNED COMPONENTS ON PROGRESSIVELY FINER SCALES. THE OVERALL MOTIVATION FOR THIS STUDY IS THE NEED FOR INCREASING RESOLUTION IN LOCATING INTERNAL ELEMENTS WITHIN CRITICAL SYSTEMS SUCH AS HIGH ENERGY PHYSICS DETECTORS AND ULTRA-PRECISION MACHINERY.