Study On Optical Fiber Process Tomography Technology

Optical fiber process tomography (OFPT) is a new technology in the field of optical fiber sensor (OFS). The probe of OFPT is small, safe, free of electromagnetic interference and has high sensitivity in low-density medium case same as OFS, more important and different is that it can detect the medium distribution and contents of the cross-section to be investigated simultaneously, which makes OFPT show potential and extensive applications in petroleum, chemical, energy, medicine, food and sanitation fields to control product quality, realize safe production and reduce the cost. On the premise of summarizing former contributions in the field, and considering the universality of the cylindrical space with circular cross-section in industry, the author develop a novel OFPT structure, on which the design theories, numerical simulation, design of experimental system for plane structure, preliminary experiment and design of applied space structure are presented. The main contents of the thesis are that:Put forward the novel OFPT pixel distribution and plane-light-path design theories and their empirical formulae. The numbers of the OFS units and their emitting rays can be decided by the requirements of image-reconstructed resolution and the size of the center unmeasured region.Develop a novel OFPT structure by the theories and simulate it by algebraic iterative reconstruction algorithm (ART). The structure includes eight OFS units uniformly distributed around the circle, where each unit emits three rays to the clockwise adjacent three units and receives three rays from counterclockwise adjacent three units. Rays cover all sixty pixels of the measured ring region. The center circular region belongs to unmeasured part for the back-up structure of the system.Design and manufacture the OFPT experimental system. Many practical problems such as waterproof, light passing and wall optical reflection are successfully solvedby specially designing an optical window, thus the positions of all optical devices such as optical fiber collimators, detectors and the windows are calculated accurately to make the collimation of all optical channels simply and easily. Take the elementary experiments and use genetic algorithm in the image reconstruction. The results show that the novel OFPT system can measure and reoccur some gas-solid two-component distributions.Design and analysis the applied space OFPT structure. The positioning accuracies of all devices and the whole system are figured out. The results show that processing and positioning requirements to optical devices in the space structure are not too high.