Development of a One-Shot Shadow MoiréSystem for Surface Profile Measurement

• Main Authors: Fa YenCheng, 程法彥
• Other Authors: Terry Yuan-Fang Chen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/cr8j77

碩士 === 國立成功大學 === 機械工程學系 === 106 === In this paper, the optical flow method and spiral quadrature transformation are applied to the shadow moiré method. One shot shadow moiré surface profile measurement system capable of dynamic measurement is designed. This system is built on setup of traditional phase-shift system. Original light source is replaced by two polychromatic light sources. Capture two sets of fringe patterns of different colors by color camera, and then the fringe pattern with a phase difference of 90 degrees is calculated by optical flow method and spiral quadrature transform. Two 90 degrees pattern can calculate the fringe phase, and the phase vale can be obtained by the phase unwrapping method. Finally the unwrapping phase can calculate the surface profile of the specimen. This paper is divided into two parts: simulation and experiment. In the simulation part, the relationship between the phase difference of the two sets of moiré patterns and the position of the light source is discussed by theory of shadow moiré method, and then the maximum height limit of the system measurement is set and a solution that exceeds the maximum height limit is proposed. When the maximum height limit is exceeded, the fringe orientation angle will different 180 degrees. So the position exceeded the limit adds 180 degrees can solve the problem. Then simulating multiple surface profile in three different sets of light source incident angles. The measurement result of the light source combination determines the most suitable light source incident angle is 45 degrees. The experimental part compares two image processing methods that can reduce the influence of light intensity of different light sources, and measures with the SMS roughness meter. Comparing the result of the system, the average error is 6.1 μm and the error standard deviation is 5.1 μm.