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. © 2016 SPIE.
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License of this version: | Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich. |
Publication type: | BookPart |
Publishing status: | publishedVersion |
Publication date: | 2016 |
Keywords english: | Fringe Projection, Image Fiber, LASER, LED, Phase-Shift, Speckle, Inspection, Laser beams, Lasers, Light sources, Machinery, Optical data processing, Phase noise, Phase shift, Projection systems, Speckle, Digital micro-mirror device, Fringe projection, Fringe projection system, High resolution image, Image fiber, Optical inspection systems, Optical measurement methods, Optical power measurements, Light emitting diodes |
DDC: | 530 | Physik |
Controlled keywords(GND): | Konferenzschrift |
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