Publications 2022
The share of the probe errors in on-machine measurements
Authors: Marta Rępalska, Adam Woźniak
The influence of the errors of touch-trigger probes for machine tools on the result of the basic measuring tasks performed by CNC was examined. The goals of the analysis were, first, to estimate an uncompensated value of the error which occurs during different qualification cycles, and second, to determine the influence of the qualification on the measurement of features such as distance, a circle and the position of corner. The investigation was based on the results of research on a few probes, for which the values of the triggering radius in the form of spatial characteristic in a laboratory were determined. The obtained results show that although the qualification cycle reduces the influence of the probe error on the measurement result and increasing the number of qualification points improves the compensation conditions, this error is not completely eliminated, and its value can reach as much as several tens of micrometres.
Optical diffraction tomography meets metrology — Measurement accuracy on cellular and subcellular level
Authors: Michał Ziemczonok, Arkadiusz Kuś, Małgorzata Kujawińska
Objective: Evaluation of the accuracy of the segmentation of simulated subsegmental infarcts using 2DSTE. Methods: Synthetic ultrasonic data were obtained using the FIELD II package and meshes obtained from FEM simulations of deformation of left ventricular (LV) models of a healthy LV and LVs with different infarcts. Hierarchical block matching method was applied to estimate displacements. Longitudinal and circumferential strain components were estimated and then averaged over small subsegments resulting from division of AHA 17 segments no 7 and 12. The infarcts were segmented in strain maps using three thresholds differing in sensitivity and specificity.
The exact infarct location derived from FEM meshes and another one obtained from FEM derived displacement maps served as the references. The classification accuracy (ACC) and centroid position error (CPE) were used to assess the results of segmentation. Results: ACC does not drop below 0.92 and 0.85 when segmentation was done using error-free and 2DSTE estimated longitudinal strain maps, respectively. ACC does not drop below 0.90 and 0.75 in the same conditions for the circumferential strain maps. The mean CPE does not exceed 2 mm and 3 mm for infarct segmented from estimated longitudinal and circumferential strain maps, respectively. Conclusion: Reduction of the strain averaging area when using 2DSTE appeared necessary for detection and segmentation of small simulated infarcts (down to 9 mm diameter) as global strain measures showed insufficient sensitivity. Significance: The advantage of strain averaging over a reduced area for segmentation of small simulated infarcts when using the 2DSTE technique has been demonstrated
