Three dimensional optical profilometry using a four-core optical fiber
Bulut, Karahan (2004) Three dimensional optical profilometry using a four-core optical fiber. [Thesis]
This study describes the use of a four-core optical fiber for the first time for measurements of three-dimensional rigid-body shapes. A fringe pattern, which was generated by the interference of four wavefronts emitted from the four-core optical fiber, was projected on an object's surface. The deformed fringe pattern containing the information of the objects height was captured by a digital CCD camera. The twodimensional Fourier transformation was applied to the image, which was digitized by using a frame grabber. After filtering this data in its spatial frequency domain by applying a bandpass filter, the two-dimensional inverse Fourier transformation was applied. A phaseunwrapping algorithm was applied to convert this discontinuous phase data to a continuous one. Finally, the shape information of the object was determined. The two-dimensional Fourier transformation analysis used in this study permitted a better signal separation and a better noise reduction. Compared to other optical profilometry techniques, which are based on fiber optics, the use of a four-core optical fiber in this study ruled out the necessity for using a fiber coupler and the alignment of fiber ends. Thus, it increased the compactness and the stability of the fringe projection system.
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