Study On Strain Sensors Based On Optical Fiber Speckle

The strain and stress are very important parameters in engineering eximination. Commonly, it is necessary to measure the strain and stress in the key location of the structure on different loads in order to evaluate the life and the state of the structure. Therefore, the strain sensors have a considerable proportion in nowadays sensors.Measuring stains by using optical fiber sensor has becoming a hotspot along with the progress in optical fiber technology. In this paper, paper we proposed a method for measuring strains based on fiber speckle, and conducted an experiment using this method.The common strain sensors (such as resistance strain gauge, fiber Bragg grating etc.) were introduced. By summarizing these technologies we drew the conclusion that strain sensor based on fiber speckle patterns was one of the new way of research in strain sensors for lower cost and higher sensitivity. The theoretic of optical fiber mode was discussed, and the expression of fiber speckle was derived in detail. And then we proposed a spatial correlation method for the better comparison of the fiber speckle patterns. In chapter 3, the image segmentation technology wasP simply introduced, which is one of the basic technologies in image processing. Considering the requirement in this paper, we laid stress on several kinds of arithmetic in image threshold segmentation, and the results were shown. And the detail experimental progress and the results were shown. At last, we completed the image progressing and spatial correlation calculation by using Lab View software.At the end of this paper, the error of results was analyzed and the problems we encountered during this study work were also discussed. The improvement methods both in theoretical and experimental were point out for the further study.