Internal Three-dimensional Off-plane Displacement Field Distribution Measuring Wavelength Scanning Interferometer Research

With the rapid development of science of composite materials, composite application domain are quickly expanding, advanced composite materials detection technology become more and more necessary. In addition, in the preparation process of the composite, the detection and control of the quality is also inseparable from the support of non-destructive testing techniques. Meanwhile, detection technology should be more accurate, faster, safe operation and non-destructive. Wavelength scanning interferometry (WSI) measuring internal three-dimensional off-plane displacement field distribution high-precisely is raised in this context. The main purpose of the article is to design and build a WSI interferometer, verify WSI technology can be applied to the field of non-destructive testing of composite materials, and provide a new platform for composite mechanics measurements.WSI technology is a new nondestructive testing technology. With the advantages of high accuracy, simple equipment and short detection time, WSI is applicable to transparent or translucent polymer composite test. And capable of measuring material internal three-dimensional off-plane displacement field distribution, it has specific advantages compared to other ways. In briefly, the testing process of WSI can be described as follows: Wavelength turning coherent light irradiates the measured object; the interference between internal and surface reflected light occurs at the wave-front; the interference pattern obtained by CCD camera; by the Fourier transform to extract the amplitude-frequency information and phase-frequency information to restore the internal three-dimensional off-plane displacement field distribution of the material, quantitatively.This article first briefly described detection field of composite materials at home and abroad, and gave details of the development of WSI technology and new progress on OCT in domestic and international; then theoretically clarified WSI technology, described the possibility of WSI used as the method of measuring the composite material; it also told how to design and build WSI interferometer system, and described key problems attended to solve; measuring the composite material internal three-dimensional off-plane displacement field distribution, proved the availability of the technology in the field of composite mechanical measuring; finally, in order to improve the portability of the WSI interferometer, and the convenience of field operations, try to separate the image acquisition subsystem from the "CCD camera--image acquisition card--computer" model image acquisition system, replace it with Linux based ARM9embedded system. This article detailed the software and hardware development process of ARM embedded systems, and the application to the WSI system, some certain results are obtained.Through three surface interference experiment, typical surface speckle interference pattern is obtained, proved the rationality of the design of the interferometer intuitively; the composite measurement Experimental results restore its internal three-dimensional distribution of off-plane displacement field, wavelength scanning interferometry technique is a powerful means of composite material mechanics measurements; the success of the image acquisition system based on Linux-ARM9opened the way for the WSI system advanced from the experimental stage to practical application.