| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 97 === A novel instrument for minuting birefringence measurements based on the Phase-Stepped Images Obtained Simultaneously (PSIOS) system, which enables three, four and six phase-stepped photoelastic images to be collected simultaneously. In three phase-stepping method, requires only three stepped photoelastic images although conventional phase-stepping methods require four images. Regarding four phase-stepping method, the difference of new instrument is that the original instrument requires four quarter-wave plates and needs to set up eight different angular magnitudes, whereas the new one requires only one quarter wave plate and changes the angle of analyzers. The plane polariscope of six phase-stepping method has improved that both circular polariscope and plane polariscope of four phase-stepping method can not get the information of full-field photoelasticity.
In addition, this article took the isoclinic information which unwrapped already into isochromatic formula to get the correct retardation. This method might not get the form of arc-tangent because there are not output quarter-wave plates in three and six phase-stepping methods. Therefore, this paper corrected it by load-stepping method. Finally, compare the results of computer simulations with theoretical solutions and demonstrate that the methods are feasible and accurate.
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