Subject Unrest

Roll-to-roll manufacturing of micro components based on advanced printing, structuring and lamination of ceramic tapes is rapidly progressing. This large-scale and cost-effective manufacturing process of ceramic micro devices is however prone to hide defects within the visually opaque tape stacks. To achieve a sustainable manufacturing with zero defects in the future, there is an urgent need for reliable inspection systems. The systems to be developed have to perform high-resolution in-process quality control at high speed. Optical coherence tomography (OCT) is a promising technology for detailed in-depth inspection and metrology. Combined with infrared screening of larger areas it can solve the inspection demands in the roll-to-roll ceramic tape processes. In this thesis state-of-art commercial and laboratory OCT systems, operating at the central wavelength of 1.3 µm and 1.7 µm respectively, are evaluated for detecting microchannels, metal prints, defects and delaminations embedded in alumina and zirconia ceramic layers at hundreds of micrometers beneath surfaces. The effect of surface roughness induced scattering and scattering by pores on the probing radiation, is analyzed by experimentally captured and theoretically simulated OCT images of the ceramic samples, while varying surface roughnesses and operating wavelengths. By extending the Monte Carlo simulations of the OCT response to the mid-infrared the optimal operating wavelength is found to be 4 µm for alumina and 2 µm for zirconia. At these wavelengths we predict a sufficient probing depth of about 1 mm and we demonstrate and discuss the effect of rough surfaces on the detectability of embedded boundaries. For high-precision measurement a new and automated 3D image processing algorithm for analysis of volumetric OCT data is developed. We show its capability by measuring the geometric dimensions of embedded structures in ceramic layers, extracting features with irregular shapes and detecting geometric deformations. The method demonstrates its suitability for industrial applications by rapid inspection of manufactured samples with high accuracy and robustness. The new inspection methods we demonstrate are finally analyzed in the context of measurement uncertainty, both in the axial and lateral cases, and reveal that scattering in the sample indeed affects the lateral measurement uncertainty. Two types of image artefacts are found to be present in OCT images due to multiple reflections between neighboring boundaries and inhomogeneity of refractive index. A wavefront aberration is found in the OCT system with a scanning scheme of two galvo mirrors, and it can be corrected using our image processing algorithm.QC 20140428Multilayer (FP7-NMP4-2007-214122

Business as Usual? Brown and the Continuing Conundrum of Race in America

In this article, Professors Robert Chang and Jerome Culp examine the state of race in America in the aftermath of the landmark Supreme Court decision of Brown v. Board of Education, focusing on the ten-year window preceding its fiftieth anniversary. Their findings reveal that while Brown established fundamental precedent in the area of race relations, racial inequality remains entrenched in a number of modern social institutions. Chang and Culp analyze this dilemma by focusing on three distinct trends. First, a cycle of inequality is driven by racial disparities in wealth and perpetuated by interlocking systems of education, housing, family, healthcare, employment, and criminal justice. Second, civil rights activists often fall short of their goals following Brown due to what the authors describe as civil rights myopias. Finally, racial remediation schemes also face major obstacles as White identity has intensified since Brown. As a result, little has changed in the ten-year window preceding Brown\u27s fiftieth anniversary and racial inequality remains a persistent problem in America