82 research outputs found
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
A Gaussian filtering method to reduce directionality on high-density point clouds digitized by a conoscopic holography sensor
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 eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than 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
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
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
- …