Textured silicone breast implants with high average surface roughness ("macrotextured") have been associated with a rare cancer of the immune system, Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL). Silicone elastomer wear debris may lead to chronic inflammation, a key step in the development of this cancer. Here, we model the generation and release of silicone wear debris in the case of a folded implant-implant ("shell-shell") sliding interface for three different types of implants, characterized by their surface roughness. The "smooth" implant shell with the lowest average surface roughness tested (R = 2.7 ± 0.6 μm) resulted in average friction coefficients of = 0.46 ± 0.11 across 1,000 mm of sliding distance and generated 1,304 particles with an average particle diameter of = 8.3 ± 13.1 μm. The "microtextured" implant shell (R = 32 ± 7.0 μm) exhibited = 1.20 ± 0.10 and generated 2,730 particles with = 4.7 ± 9.1 μm. The "macrotextured" implant shell (R = 80 ± 10 μm) exhibited the highest friction coefficients, = 2.82 ± 0.15 and the greatest number of wear debris particles, 11,699, with an average particle size of = 5.3 ± 3.3 μm. Our data may provide guidance for the design of silicone breast implants with lower surface roughness, lower friction, and smaller quantities of wear debris.

The application of surface topography measurement methods to the field of firearm and toolmark analysis is fairly new. The field has been boosted by the development of a number of competing optical methods, which has improved the speed and accuracy of surface topography acquisitions. We describe here some of these measurement methods as well as several analytical methods for assessing similarities and differences among pairs of surfaces. We also provide a few examples of research results to identify cartridge cases originating from the same firearm or tool marks produced by the same tool. Physical standards and issues of traceability are also discussed.

Recent concerns about subjectivity in forensic firearm identification have motivated the development of algorithms to compare firearm tool marks that are imparted on ammunition and to generate quantitative measures of similarity. In this paper, we describe an algorithm that identifies impressed tool marks on a cartridge case that are both consistent between firings and contribute strongly to a surface similarity metric. The result is a representation of the tool mark topography that emphasizes both significant and persistent features across firings. This characteristic surface map is useful for understanding the variability and persistence of the tool marks created by a firearm and can provide improved discrimination between the comparison scores of samples fired from the same firearm and the scores of samples fired from different firearms. The algorithm also provides a convenient method for visualizing areas of similarity that may be useful in providing quantitative support for visual comparisons by trained examiners.

Important to the success of additive manufacturing (AM) is the ability to inspect and qualify parts. The research community is pushing to identify correlations between part function and surface topography, yet little guidance specific to AM surface measurement exists. Thus, development of inspection methods for surface finish are required. In laser powder bed fusion (LPBF) AM, parts are built through a complex process with many variables, and the length scales of interest on the surface cover a wide range. Full characterization of the surface is time consuming and costly as high resolution in surface measurements decreases field-of-view (FoV), requiring stitching multiple FoVs to cover large areas. Statistical methods exist to estimate the maximum value based on a sample of FoVs, but are not yet commonplace in AM surface measurement. The goal of this work is to understand the use of these statistical methods in the estimation of maximum area valley depth ( ) of a surface, an extreme value parameter, for which researchers have already found relationship to fatigue life. This work also investigates the effect of microscope objective, measurement region size, and nesting index of areal filters on . A large (i.e., greater than 40 mm × 40 mm) planar LPBF surface is fabricated in nickel superalloy 625 and measured using a focus variation microscope with a objective and again with a objective. Results show that there is little difference in the maximum value of between the two objectives, but the nesting index does have some effect. Results also show that a Type 1 Generalized Extreme Value, or Gumbel, distribution can be used to accurately estimate the maximum value of for a surface from a small set of measurements, providing a framework for users to develop inspection routines that balance measurement time and accuracy of estimation.

The vertical scale calibration of an interferometric microscope is important for establishing traceability of surface topography measurements to the International System of Units (SI) unit of length, the meter. Building on the calibration procedure for the amplification coefficient developed by de Groot and Beverage [Proc. SPIE , 952610 (2015)], this paper describes a calibration procedure that yields the response curve for the entire vertical scan motion of a coherent scanning interferometric microscope. The method requires only a flat mirror as an artifact, a narrow band spectral filter, an aperture to reduce the effective numerical aperture, and the ability to raise and lower the microscope head so that the center of the interferogram can be varied within the scan range. The local frequency of the interferogram is determined by fitting sections of the interferogram to a sinusoidal function. The nonlinearity determined from the local frequency data can be used to estimate the uncertainty in uncorrected vertical height measurements. We describe how optical profile data can be corrected for nonlinearity due to dynamic effects in the scan motion and show that the correction improves the reproducibility of step height measurements by at least a factor of three and close to that of the repeatability.