Influence of surface location within depth of field on measuring by a conoscopic holography sensor integrated in a machining centre

Estudio de la influencia de la posición en el campo de trabajo sobre los resultados de medición de un sensor de holografía conoscópica integrado en un centro de mecanizado.In this work, a Conoscopic Holography (CH) sensor integrated in a Machining Centre (MC) was used for analysing how the measurements taken are influenced by the location of the digitized surface within depth of field (DOF). With this aim, two different digitizing strategies were conducted on a stepped specimen with flat surfaces. In the first strategy each step of the specimen was located at different positions within DOF whereas the CH sensor was kept at a constant height along the scanning of all steps. In the second strategy the sensor height was adapted so that each step was scanned at the same distance within DOF. The comparison between both strategies was performed by calculating the discrepancies between measurements taken by the CH sensor and those obtained by a touch probe (TP) also installed in the MC. Finally, the study provides a series of recommendations for practical application of the sensor.This work is supported by the Spanish Ministry of Economy and Competitiveness and FEDER (DPI2012-30987), the Regional Ministry of Economy and Employment of the Principality of Asturias (Spain) (SV-PA-13-ECOEMP-15) and the Government of the Principality of Asturias through the Programme “Severo Ochoa” 2014 of PhD grants for research and teaching (BP14-049)

A comparison between discrete and continuous scanning with conoscopic holography

Low density digitizing is a suitable approach for verification distances between pairs of machined flat surfaces. When defining a digitizing procedure of this type of features, two approaches could be applied: discrete or continuous scanning. Discrete Scanning (D) is performed with a static sensor, but the information for each single measurement comes from a constrained area. On the other hand, since Continuous Scanning (C) is carried out with a moving sensor, the information for each single measurement comes from a swept area. In this work, a comparison between these two approaches, when digitizing with a Conoscopic Holography sensor, is performed. The main objective is to establish their influence upon surface reconstruction quality and, thereafter, upon measurement reliability.This work is supported by the Spanish Ministry of Economy and Competitiveness and FEDER (DPI2012-30987), the Regional Ministry of Economy and Employment of the Principality of Asturias (Spain) (SV-PA-13-ECOEMP- 15) and the Government of the Principality of Asturias through the Programme “Severo Ochoa” 2014 of PhD grants for research and teaching (BP14-049).Análisis de diferencias de resultados en términos metrológicos de distancia 3D entre planos, utilizando diferentes estategias de digitalizado con un sensor de Holografía Conoscópica integrado en una máquina de medición por coordenadas

Influence of roughness on conoscopic holography digitizing of DIN34CrMo4 surfaces

AbstractConoscopic Holography is a non-contact digitizing technique used in inspection and reverse engineering tasks. A laser beam is projected onto a surface, and its reflection generates a holographic pattern inside the sensor. This pattern is later analysed and the distance between sensor and surface is calculated. Like other optical techniques, conoscopic holography shall be affected by surface properties and ambient conditions. This works deals with the influence of surface roughness and manufacturing process on the quality of digitizing. 34CrMo4 steel test specimens have been manufactured to obtain four different Ra levels. Two different manufacturing process, electrical discharge machining (EDM) and ball-end milling (BEM) have been also considered. Quality of the digitized point clouds under different sensor configurations has been analysed, in order to provide a recommendation for optimal capture conditions

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO