This dissertation deals with non-contact 3-dimensional coordinate metrology using a video probe with a specific aim to profile inspection of shadow masks. The main emphasis was given to automatic image focusing so that heights of the flexible perforated surface of shadow mask can be measured in non-contact manner on a conventional CNC coordinate measuring machine. In general, autofocusing can be performed simply by high spatial image frequencies as the degree of defocus reduces. Exsiting autofocusing algorithms rely mainly upon the Sobel or Laplacian operator whose filtering performances are predestined by the window size of convolution operation. Thus they often fail to provide a good reference signal for autofocusing. However, the algorithm proposed in this study is in fact an extension of existing algorithms, which can modify its filtering performances by considering the limited optical characteristics of the video probe used and moreover according to the inherent spatial attributes of the object being measured. The modification is maded by using the zero-padding method that adds suitable number of zeros in the window mask operator of the Sobel or Laplacian to shift its frequency transfer function. Finally, it has been proved through experiments that the new algorithm is superior to existing ones, providing better performances especially in terms of signal sharpness and smoothness improving measurement repeatability.
Static and fatigue behavior of optical fiber embedded in composite laminate is studied. Comparing the failure strain of cured and uncured optical fibers indicated that strength degradation caused by thermal treatment during the composite laminate curing cycle is serious.
The strength of optical fibers embedded within the composite laminate was increased slightly compared to the single fiber strength. Effects of transverse matrix cracks on the failure of optical fiber embedded in transverse ply of cross ply laminate are assessed by the combination of the weakest link theory and the shear lag analysis.
Through fatigue experiment of optical fiber embedded composite laminates, it is found that the fatigue life of optical fiber embedded in cross ply laminate is dependent on the fatigue behavior of transverse matrix crack, while the decrease in fatigue life of optical fiber embedded in unidirectional laminate with increasing maximum applied stress is relatively small.