Surface and topography metrology in firearm evidence identification and engineering surface quality control

This thesis is a topical review on the application of Surface and Topography Metrology in Firearm Evidence Identification and Engineering Surface Quality Control. It summarizes my research work at the National Institute of Standards and Technology (NIST) from 1987 to present, where I’m a Project Lead for the Forensic Topography and Surface Metrology since 1997. I started my research in surface metrology since 1982 -- after my MS study at the Harbin Institute of Technology (HIT, Harbin, China) from 1978 to 1981. In 1985, I designed, manufactured and patented the Precision Random Profile Roughness Specimens in Beijing aimed to provide a reference standard for quality control of smooth engineering surfaces [1]. These specimens were manufactured with Ra values ranging from 0.015 μm to 0.1 μm -- less than 1/10 of the similar specimens developed by PTB (Physikalisch-Technische Bundesanstalt) in Germany. These specimens were successfully used by U.S. manufacturers for measurement unification and quality control of smooth engineering surfaces, and were included in ASME B46 surface standard in 1995. Microform metrology is a subfield of surface metrology that involves surface measurements of complex geometry features on the micrometer scale. In 1995, I led a team at NIST which established a Microform Calibration System with the lowest calibration uncertainty in the world for calibration of Rockwell hardness (HR) diamond indenters. Based on the precision calibration of HR indenters and the control of other influencing quantities, I proposed a “Metrological Approach” to unifying international HRC scales with metrological traceability. I led an international HRC comparison among five National Metrological Institutes (NMIs). The comparison results strongly supported the proposed Metrological Approach. I drafted a joint paper for five NMIs entitled “Establishing a worldwide unified Rockwell hardness scale with metrological traceability” which was published at the Metrologia 34, 1997 in Paris [4]. Surface and topography metrology provides strong support to firearm evidence identifications. Based on my experience in developing surface standards, measurement systems, uncertainty and traceability procedures, I led a research team which developed the NIST Standard II Reference Material (SRM) Bullets and Cartridge Cases, and the NIST 2D/3D Topography Measurement System [5]. We formulated a National Traceability and Quality System using the SRM Bullets and Cartridge Cases to support ballistics identifications within the National Integrated Ballistics Information Network (NIBIN) in the United States [6]. I have recently invented a Congruent Match Cells (CMC) method for accurate ballistics identification and error rate estimation [7], which can serve as a statistical foundation for estimating error rates in firearm evidence identifications, thus emulating methods used for forensic identification of DNA evidences [8].