Details
| Original language | English |
|---|---|
| Article number | 3407 |
| Pages (from-to) | 239-246 |
| Number of pages | 8 |
| Journal | Measurement |
| Volume | 73 |
| Publication status | Published - 1 Jun 2015 |
Abstract
Abstract To be able to perform inline inspection of complex geometries, which exhibit for example undercuts or internal structures, a new endoscopic micro fringe projection system has been developed. It is designed to perform areal measurements for tool inspection inside the limited space of metal forming presses by employing flexible image fibers to couple the measurement system's camera and projector to a compact sensor head. The projector features a laser light source and a digital micro-mirror device to generate high-contrast fringe patterns. To increase the depth of field of the sensor heads, custom gradient-index lenses have been designed as an approximation to the Scheimpflug principle. Challenges arise for both calibration and phase measuring algorithms from the optics, as well as from the reduction in resolution introduced by the fiber bundles. This paper presents an evaluation of two different system models for the endoscopic fringe projection system, which are based on the pinhole camera model and a black box model. An automated calibration process, which gathers the calibration data for two calibration algorithms that are robust to artifacts introduced by the optical path, is demonstrated. Based on a comparison of measurements, differences between the two modeling approaches are discussed. Finally, results of measurements of a demonstrational metal forming tool are shown as an application example.
Keywords
- Calibration, Endoscopy, Fringe projection, Inline inspection, Metal forming
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Instrumentation
- Engineering(all)
- Electrical and Electronic Engineering
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In: Measurement, Vol. 73, 3407, 01.06.2015, p. 239-246.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Evaluation of system models for an endoscopic fringe projection system
AU - Matthias, Steffen
AU - Kästner, Markus
AU - Reithmeier, Eduard
N1 - Funding information: The authors would like to thank the German Research Foundation (DFG) for funding the project B6 “Endoscopic geometry inspection” within the Collaborative Research Center (CRC)/ TR 73.
PY - 2015/6/1
Y1 - 2015/6/1
N2 - Abstract To be able to perform inline inspection of complex geometries, which exhibit for example undercuts or internal structures, a new endoscopic micro fringe projection system has been developed. It is designed to perform areal measurements for tool inspection inside the limited space of metal forming presses by employing flexible image fibers to couple the measurement system's camera and projector to a compact sensor head. The projector features a laser light source and a digital micro-mirror device to generate high-contrast fringe patterns. To increase the depth of field of the sensor heads, custom gradient-index lenses have been designed as an approximation to the Scheimpflug principle. Challenges arise for both calibration and phase measuring algorithms from the optics, as well as from the reduction in resolution introduced by the fiber bundles. This paper presents an evaluation of two different system models for the endoscopic fringe projection system, which are based on the pinhole camera model and a black box model. An automated calibration process, which gathers the calibration data for two calibration algorithms that are robust to artifacts introduced by the optical path, is demonstrated. Based on a comparison of measurements, differences between the two modeling approaches are discussed. Finally, results of measurements of a demonstrational metal forming tool are shown as an application example.
AB - Abstract To be able to perform inline inspection of complex geometries, which exhibit for example undercuts or internal structures, a new endoscopic micro fringe projection system has been developed. It is designed to perform areal measurements for tool inspection inside the limited space of metal forming presses by employing flexible image fibers to couple the measurement system's camera and projector to a compact sensor head. The projector features a laser light source and a digital micro-mirror device to generate high-contrast fringe patterns. To increase the depth of field of the sensor heads, custom gradient-index lenses have been designed as an approximation to the Scheimpflug principle. Challenges arise for both calibration and phase measuring algorithms from the optics, as well as from the reduction in resolution introduced by the fiber bundles. This paper presents an evaluation of two different system models for the endoscopic fringe projection system, which are based on the pinhole camera model and a black box model. An automated calibration process, which gathers the calibration data for two calibration algorithms that are robust to artifacts introduced by the optical path, is demonstrated. Based on a comparison of measurements, differences between the two modeling approaches are discussed. Finally, results of measurements of a demonstrational metal forming tool are shown as an application example.
KW - Calibration
KW - Endoscopy
KW - Fringe projection
KW - Inline inspection
KW - Metal forming
UR - http://www.scopus.com/inward/record.url?scp=84930942913&partnerID=8YFLogxK
U2 - 10.1016/j.measurement.2015.05.024
DO - 10.1016/j.measurement.2015.05.024
M3 - Article
AN - SCOPUS:84930942913
VL - 73
SP - 239
EP - 246
JO - Measurement
JF - Measurement
SN - 0263-2241
M1 - 3407
ER -