The K-space Theory, Algorithms And Applications Based On Phase Control Optical Coherence Tomography

With the rapid development of science of composite materials, the applications of composite materials is become more and more widely, But during the preparation of the material, due to the influence of process parameters is unstable, the material itself is defective, human action and environmental factors, make the surface or internal of the material may be gaps, cracks and delamination defects, leading to a decline in the quality of material, so there must have advanced detection technology to detect the quality of composites. The nondestructive detection methods currently used are:ray inspection, magnetic particle testing, penetration testing, eddy current testing and ultrasonic testing and other methods, but each has its advantages and disadvantages, thus new detection technology with nondestructive detection, high accuracy, high speed, operational safety is needed. Wavelength scanning interferometry(WSI) technology can exactly meet these requirements, this is the background of this paper. The main purpose of this paper is:(1) discovery new algorithm-k-space theory, which is applied in the WSI system, used to measure the depth information within the material;(2) using C++language to write algorithm program to process experimental data.Wavelength scanning interferometry(WSI) technology is a new nondestructive detection technology, which is very suitable for the detection of transparent, translucent composite materials, has the advantages of high measuring precision, short detection time, etc., and have the ability to measure the three-dimensional material internal displacement field distribution information, has its specific advantages compared with other detection techniques. In fact, the wavelength scanning interferometry technique is the use of the object with coherent light wavelength laser irradiation temperature change, while reflecting internal surface of the object and the optical interference occurs at the wave-front, the interference patterns collected by the camera, and using 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 paper mainly introduces the domestic and international research progress of the wavelength scanning interferometry technology and optical coherence tomography(OCT); then from the perspective of the theory expounded WSI technology base, illustrates its possibilities in material measurement; simply introduced the basic knowledge of wave optics, and highlights the optical interferometer commonly used in engineering as well as the interferometer principle and usage scenarios, provides the basic for the section of experimental device; the theory of scalar diffraction theory, the holographic reconstruction and tomographic reconstruction is derived in detail in this paper, the theory is applied to the WSI system, then come to express their k-space, and provides a theoretical basis for the deep displacement information of WSI technique to measure the internal composite; Finally, by using C++language program related algorithms to handle the data which was collected by experimental, include:(1) cut picture program;(2) the fast Fourier(FFT) algorithm;(3) the Chirp-z transform(CZT) algorithm;(4) random sampling Fourier transform(RSFT) algorithm; described in detail the principle of the algorithm and the specific implementation steps, then analysis and comparison of results obtained using this algorithm compared with the MATLAB experimental data, verify the feasibility of this algorithm.