Three optical instruments including an interferometric microscope, a Nipkow disk confocal microscope and a laser scanning confocal microscope are used for the measurements of bullet profile signatures of a National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2460 standard bullet. The 2D profile signatures are compared with the virtual bullet standard signature established by a stylus-based measurement system at NIST. The bullet signature differences are quantified by the maximum cross-correlation function CCFmax. If the compared signatures were exactly the same, CCFmax would be 100%. Comparison results show close agreement among the four techniques for bullet profile signature measurements. The average CCFmax values are higher than 90%. This supports the possibility of using surface topography techniques for ballistic identifications as an alternative to the current technology based on image comparisons.
Citation: Measurement Science & Technology
Pub Type: Journals
auto-correlation function, confocal microscope, cross-correlation function, standard bullet, standard reference material, topography comparison