Research On Three-dimensional Measurement System Based On Infrared Fringe Projection

Color fringe projection technology is a multi-channel optical measurement method. This technology not only has advantages of non-contact, full- field, high accuracy, and fast data processing, but also improve the utilization of color channels and accelerate acquisition speed, so that it is becoming a hot topic in research and application fields of three-dimensional optical measurement. However, color fringe projection technology can’t avoid effects of ambient light and crosstalk between color channels still can’t be completely resolved, which reduce the measurement accuracy. Infrared(IR) light can solve these two problems well due to its spectral characteristics. The exiting 3D measurement systems involving IR light always use multiple cameras to capture images from different angles. The relationship between these cameras need to be built by tedious calculations, so that the measurement accuracy is affected.This dissertation presents a three-dimensional(3D) measurement system based on multi-channel IR fringe projection technique and develops a suite of system control software in Microsoft Visual Studio 2010. The system uses IR fringe to accurately measure 3D data of objects to avoid influence of ambient light and crosstalk between channels, with visible light to determine the absolute fringe order. In addition, the system acquires IR and visible channels information from the same viewpoint with the same optical path through a 2CCD camera, without needing complicate coordinate conversion to complete 3D measurement of objects. In order to obtain pixel position deviation between color channels, this dissertation proposes a novel pixel deviation calculation and correction method by using absolute phase data, and shows its implementation for 2CCD camera and the measuring system. Pixel correspondence in different color channels is found by absolute phases of two mutually perpendicular directions as unique code of each pixel position. An interpolation method has been used to further improve accuracy of pixel deviation calculation and correction to reach the level of subpixel accuracy. Finally, a series of experiments have been carried out to prove the performance of the 3D system, and verify the validity and accuracy of pixel deviation correction method. Based on continuous phase information, the method can correct deviation pixel-by-pixel in the full- field with advantage of high precision. Therefore, it can solve the problems of pixel deviation between channels in multi-channel 3D measurements and will promote the development of multi-channel 3D measurement technology.