System And Algorithms Of Depth 3D Profilemetry Measurement Based On Wavenumber-scanning Interferometry

The application of depth three-dimensional (3D) profiemetry measurement is more and more important in the field of composite detection and ultra-precision machining at present. The high accuracy methods are typically based on the theory of laser interference. Wavenumber-scanning interferometry (WSI) is a kind of laser interference method. WSI is an important direction of high precision detection. When its case temperature was tuned. During the period, N interference images were acquired by the CCD camera. Finally all the time-resolved interferometry image sequences were sampled by random sample fourier transform, then by using phase unwrapping algorithm, the depth 3D contour of the measured surface was restored with high precision. Accuracy of the depth 3D profilometry is highly depended on the range of laser output wavelength. In fact, the wavenumber range of the laser output is limited. To solve the above problem, the main research contents are as follows:(1) A depth 3D profilometry measurement system based on the theory of michelson’s interferomete is established;(2) In order to improve the accuracy of depth 3D profilometry when the range of laser output wavelength becomes narrow, a novel algorithm called Eigenvalue Decomposition and Least Squares Algorithm (EDLSA) is proposed in this paper.The main content of this disertation is as follow:firstly the background and the significance of profilemetry measurement and the methods of 3D profilemetry measurement are introduced in detail. To solve the depth 3D profilemetry problem, depth 3D profilemetry measurement based on wavenumber scanning interferometry was introduced and its development was discussed also. Then wavenumber scanning interference technology applied in depth 3D profilemetry measurement is analyzed. This includes laser wavenumber scanning technology, monitoring the wavenumber series of the diode laser output on-line, random sample fourier transform theory and phase profile measurement mathematical model was established based on wavenumber scanning interferometry. Depth 3D profilometry measurement using wavenumber-scanning interferometry is proved theoretically. The mathematical formula for calculating the peak frequency and the peak phase of the depth multi-surface interference is derived by EDLSA. Simulation shows the feasibility and superiority of the proposed algorithm applied in depth 3D profilemetry measurement system based on WSI technique. Finally a depth 3D profilometry measurement system with high accuracy is build, and design two groups of experimental to verify the performance of EDLSA. Experiments results show that the proposed algorithm EDLSA can significantly improve the accuracy of depth 3D profilemetry measurement.