Moire Method to Measure Surface Depth Profiles on Unevenly Corroded Metals

介绍了一种由微机、电视摄像机和图像输入处理单元组成的测量不均匀腐蚀金属表面三维轮廓的自动化系统。当试样向下移动时，照明光和光栅呈现出由亮条纹和暗条纹组成的云纹图案投射到试样上。每个点的深度是通过分析亮度变化作为到达暗条纹中心所需的步数来确定的。用维氏压痕和钻孔对该系统进行了标定，测量深度范围为50 ~ 360 <微> m。该系统测量的深度与光学显微镜测量的深度一致，误差在10 <微> m。应用于暴露在流动海水中的黄铜样品和低合金钢。

An automated system is presented which consists of a microcomuter, a TV camera and an image input processing unit to measure three dimensional profiles for unevenly corroded metal surfaces. When a specimen is moved downward, an illumination light and a grating present moire patterns projected onto the specimen which consist of bright and dark fringes. Depth of each point is determined by the analysis of the brightness variation as the number of steps required to reach the dark fringe center. Calibrations of the system were made with Vickers indentations and drilling holes with depths ranging from 50 to 360 <micro> m. The depths measured by this system coincided with the ones done by an optical microscope within error of 10 <micro> m. The applications were made with a brass specimen and a low alloyed steel which had been exposed in flowing sea water.