High-Precision 3D Morphology Measurement by Digital Gatling Method Based on Structured Light
LUO Gang-yin1, 2, TANG Yu-guo1*, QIAO Pei-yu1, 2, WANG Bi-dou1, JIA Zan-dong1, XU Zhong1
1. Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：In order to measure the microscopic 3D morphology of the objects with high-precision, a 3D texture measurement system of digital gatling based on structured light was designed, which can calculate the 3D height information with the analytic phase method. First, the authors collected sixteen equal step phase images by the four-step equal step method, and calculated their main value by dividing them into four groups. Then，the authors found the average as the final phase main value. The pretreatment on the fringe was done by the adaptive Wiener filter and wavelet multi-threshold method to eliminate the various effects of noise, projector distortion and CCD camera distortion. Besides, gradient-oriented phase unwrapping algorithm based on multi-frequency was introduced to avoid phase discontinuity point in the course phase unwrapping, and it was proven to be effective and stable. Experiments showed that the system’s 3D resolution was 2.75 μm, and the high degree accuracy was better than 0.5 μm, when the system was running with the fringe parameter p0=22.7 mm-1. In addition, the system has many advantages such as fast measuring, simple operation and non-contact, which can meet the need of the high precision measurement requirements for the microscopic 3D morphology.
Key words：3D morphology;Phase main value;Multi-threshold;Phase unwrapping;Multi-frequency gradient-oriented
