Details
| Original language | English |
|---|---|
| Title of host publication | Optical Sensing and Detection IV |
| Editors | Francis Berghmans, Anna G. Mignani |
| Publisher | SPIE |
| Number of pages | 7 |
| ISBN (electronic) | 9781510601444 |
| Publication status | Published - 29 Apr 2016 |
| Event | Optical Sensing and Detection IV - Brussels, Belgium Duration: 3 Apr 2016 → 7 Apr 2016 |
Publication series
| Name | Proceedings of SPIE - The International Society for Optical Engineering |
|---|---|
| Volume | 9899 |
| ISSN (Print) | 0277-786X |
| ISSN (electronic) | 1996-756X |
Abstract
The inspection of functional elements is a crucial part of modern production cycles. However, with higher integration of production machinery and products, the accessibility for measurement systems is more and more limited. A solution for this problem can be found in endoscopy techniques, which are able to transport the image information for optical measurement methods. In this paper, an optical inspection system based on the fringe projection proifllometry technique is presented. The iflber-optic fringe projection system uses two high-resolution image iflbers to connect a compact sensor head to the pattern generation and camera unit. In order to keep inspection times low, the system is developed with particular focus on fast projection times. This can be achieved by using a digital micro-mirror device, which is capable of projecting grey-scale patterns at a rate of more than 10 images per second. However, due to the low numerical aperture of the optical iflbers, a limiting factor for the pattern rate is the illumination path of the pattern generator. Two different designs of the illumination path are presented, which are based on a LASER light source as well as a LED light source. Due to low beam divergence and high intensities LASERs are well suited for iflber coupling. Unfortunately, the coherent property of the light has negative effects in certain measurement applications, as interference patterns, the so called speckle, appear on rough surfaces. Although speckle reducing methods are employed in the LASER beam path, the emergence of interference cannot be prevented completely. As an alternative, an illumination path based on a LED light source is demonstrated. To compare the effects of the speckle, based on measurements on a planar calibration standard both designs are compared in terms of phase noise, which is directly related to the noise in the reconstructed 3-D point data. Additionally, optical power measurements of both methods are compared to give an estimation of coupling eiflciency. Finally, the capabilities of the system are shown based on measurements of a micro-contour standard.
Keywords
- Fringe Projection, Image Fiber, LASER, LED, Phase-Shift, Speckle
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Physics and Astronomy(all)
- Condensed Matter Physics
- Computer Science(all)
- Computer Science Applications
- Mathematics(all)
- Applied Mathematics
- Engineering(all)
- Electrical and Electronic Engineering
Cite this
- Standard
- Harvard
- Apa
- Vancouver
- BibTeX
- RIS
Optical Sensing and Detection IV. ed. / Francis Berghmans; Anna G. Mignani. SPIE, 2016. 989905 (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9899).
Research output: Chapter in book/report/conference proceeding › Conference contribution › Research › peer review
}
TY - GEN
T1 - Comparison of LASER and LED illumination for fiber optic fringe projection
AU - Matthias, Steffen
AU - Kästner, Markus
AU - Reithmeier, Eduard
PY - 2016/4/29
Y1 - 2016/4/29
N2 - The inspection of functional elements is a crucial part of modern production cycles. However, with higher integration of production machinery and products, the accessibility for measurement systems is more and more limited. A solution for this problem can be found in endoscopy techniques, which are able to transport the image information for optical measurement methods. In this paper, an optical inspection system based on the fringe projection proifllometry technique is presented. The iflber-optic fringe projection system uses two high-resolution image iflbers to connect a compact sensor head to the pattern generation and camera unit. In order to keep inspection times low, the system is developed with particular focus on fast projection times. This can be achieved by using a digital micro-mirror device, which is capable of projecting grey-scale patterns at a rate of more than 10 images per second. However, due to the low numerical aperture of the optical iflbers, a limiting factor for the pattern rate is the illumination path of the pattern generator. Two different designs of the illumination path are presented, which are based on a LASER light source as well as a LED light source. Due to low beam divergence and high intensities LASERs are well suited for iflber coupling. Unfortunately, the coherent property of the light has negative effects in certain measurement applications, as interference patterns, the so called speckle, appear on rough surfaces. Although speckle reducing methods are employed in the LASER beam path, the emergence of interference cannot be prevented completely. As an alternative, an illumination path based on a LED light source is demonstrated. To compare the effects of the speckle, based on measurements on a planar calibration standard both designs are compared in terms of phase noise, which is directly related to the noise in the reconstructed 3-D point data. Additionally, optical power measurements of both methods are compared to give an estimation of coupling eiflciency. Finally, the capabilities of the system are shown based on measurements of a micro-contour standard.
AB - The inspection of functional elements is a crucial part of modern production cycles. However, with higher integration of production machinery and products, the accessibility for measurement systems is more and more limited. A solution for this problem can be found in endoscopy techniques, which are able to transport the image information for optical measurement methods. In this paper, an optical inspection system based on the fringe projection proifllometry technique is presented. The iflber-optic fringe projection system uses two high-resolution image iflbers to connect a compact sensor head to the pattern generation and camera unit. In order to keep inspection times low, the system is developed with particular focus on fast projection times. This can be achieved by using a digital micro-mirror device, which is capable of projecting grey-scale patterns at a rate of more than 10 images per second. However, due to the low numerical aperture of the optical iflbers, a limiting factor for the pattern rate is the illumination path of the pattern generator. Two different designs of the illumination path are presented, which are based on a LASER light source as well as a LED light source. Due to low beam divergence and high intensities LASERs are well suited for iflber coupling. Unfortunately, the coherent property of the light has negative effects in certain measurement applications, as interference patterns, the so called speckle, appear on rough surfaces. Although speckle reducing methods are employed in the LASER beam path, the emergence of interference cannot be prevented completely. As an alternative, an illumination path based on a LED light source is demonstrated. To compare the effects of the speckle, based on measurements on a planar calibration standard both designs are compared in terms of phase noise, which is directly related to the noise in the reconstructed 3-D point data. Additionally, optical power measurements of both methods are compared to give an estimation of coupling eiflciency. Finally, the capabilities of the system are shown based on measurements of a micro-contour standard.
KW - Fringe Projection
KW - Image Fiber
KW - LASER
KW - LED
KW - Phase-Shift
KW - Speckle
UR - http://www.scopus.com/inward/record.url?scp=84997285859&partnerID=8YFLogxK
U2 - 10.1117/12.2225601
DO - 10.1117/12.2225601
M3 - Conference contribution
AN - SCOPUS:84997285859
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Optical Sensing and Detection IV
A2 - Berghmans, Francis
A2 - Mignani, Anna G.
PB - SPIE
T2 - Optical Sensing and Detection IV
Y2 - 3 April 2016 through 7 April 2016
ER -