Using advanced depth-sensitive hardness measurements, the homogenous nucleation of dislocations has been observed in dislocation-free single crystals. This process is related to a sudden displacement jump in the force-displacement curve. The mechanical stress for the set-in of this pop-in effect has been estimated with the Hertzian elastic contact theory. Experimental results of dislocation loop nucleation show good agreement with the continuum theory of dislocations. Electron microscopy provides a direct proof of dislocation nucleation during nanoindentation.

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Achieving traceability is crucial for complex measurement techniques, especially for coordinate measuring machines (CMMs). For CMMs using tactile probes, traceability can for certain measurements be achieved using model-based uncertainty budgets. Up to now, uncertainty simula-tions could be used applicable only for tactile CMM measurements of regular geometries, but are available as an add-on for different CMMs. This procedure is accepted by guidelines and inter-national standards (VDI/VDE 2617-7, supplement 1 [1] to GUM). Furthermore, empirical ap-proaches to assess the measurement uncertainty by means of calibrated workpieces or prior know-ledge exist or are under development. These approaches can as a matter of principle also be used for CMMs featuring computed tomography (CT). In this paper, the empirical assessment of the mea-surement uncertainty of the upcoming measurement technology CT [2, 3] will be discussed uniting the present approaches and the current knowledge, with the focus being on the applicability of con-cepts for users in industry. For this purpose, the influences on dimensional CT measurements are analyzed and evaluated, taking the measurement data of a current industrial micro CT system as a basis.

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This paper presents procedures and standards for the testing of tactile and optical microsensors and micro-computed tomography (micro-CT) systems for coordinate metrology. The tests are analogue to the well-established tests for classical coordinate measuring machines (CMM) and assess local and global sensor characteristics. For this purpose, adequate and miniaturized reference standards were manufactured, calibrated and tested. In addition, task-specific reference standards have been realized to determine special sensor characteristics, such as the maximum slope angle measurable by optical sensors or specific errors of tactile–optical microprobes measuring deep micro-holes.