IN-SITU MEASUREMENT OF DIMENSIONS AND SURFACE PROFILE OF AXISYMMETRIC OBJECTS USING FRINGE PROJECTION TECHNIQUE

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Farahi, N. (2018). IN-SITU MEASUREMENT OF DIMENSIONS AND SURFACE PROFILE OF AXISYMMETRIC OBJECTS USING FRINGE PROJECTION TECHNIQUE. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

Fringe projection technique has been a powerful tool for 3D metrology and surface profilometry with high repeatability. However, for in-situ measurement of objects with highly specular surfaces, large dimensions, and large varying slopes, acquiring high precision measurements is a challenge. We developed an inverse projected-fringe technique for in-situ measurement of form and surface profile of axisymmetric parts having those characteristics. A computer simulation-based method, the CAD model and a master-part were used to produce the inverse fringes as well as to find the best measurement trace passing through the symmetrical axis of the part that offers the best signal to noise ratio. This technique measures the deviation from a CAD model or a master-part and provides an accuracy of better than 10 microns for the part with a radial dimension of about 10 cm. It is shown that the proposed technique improves the signal to noise ratio and the repeatability of the system compared to the standard fringe projection technique, in particular for those areas with steep slopes. An in-situ system has been developed for on-machine repeatability and reproducibility tests. The tests showed that the repeatability and reproducibility of the system are still better than 10 microns. Finally, a hybrid method has been used to produce the inverse projected-fringe patterns for the inspection of axisymmetric parts having complex surface structures in addition to large dimensions and large varying slopes.

Details
Author

Farahi, Navid

Title

IN-SITU MEASUREMENT OF DIMENSIONS AND SURFACE PROFILE OF AXISYMMETRIC OBJECTS USING FRINGE PROJECTION TECHNIQUE

Physical Description

1 online resource (80 pages) : PDF

Date

2018

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Fringe projection technique has been a powerful tool for 3D metrology and surface profilometry with high repeatability. However, for in-situ measurement of objects with highly specular surfaces, large dimensions, and large varying slopes, acquiring high precision measurements is a challenge. We developed an inverse projected-fringe technique for in-situ measurement of form and surface profile of axisymmetric parts having those characteristics. A computer simulation-based method, the CAD model and a master-part were used to produce the inverse fringes as well as to find the best measurement trace passing through the symmetrical axis of the part that offers the best signal to noise ratio. This technique measures the deviation from a CAD model or a master-part and provides an accuracy of better than 10 microns for the part with a radial dimension of about 10 cm. It is shown that the proposed technique improves the signal to noise ratio and the repeatability of the system compared to the standard fringe projection technique, in particular for those areas with steep slopes. An in-situ system has been developed for on-machine repeatability and reproducibility tests. The tests showed that the repeatability and reproducibility of the system are still better than 10 microns. Finally, a hybrid method has been used to produce the inverse projected-fringe patterns for the inspection of axisymmetric parts having complex surface structures in addition to large dimensions and large varying slopes.

Genre

doctoral dissertations

Subjects--Topics

Optics
Physics

Degree

Ph.D.

Keywords

Fringe Projection
Inverse Fringe
Inverse Projected-Fringe
Optical Metrology
Quality Control
Structured Light

Subject Area

Optical Science & Engineering

Advisor(s)

Farahi, Faramarz

Committee Members

Davies Allen, Angela
Porras-Aguilar, Rosario
Kazemi, Mohammad

Degree Note

Thesis (Ph.D.)--University of North Carolina at Charlotte, 2018.

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Rights Holder Information

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Identifier

Farahi_uncc_0694D_11942

Permalink

http://hdl.handle.net/20.500.13093/etd:878