Study On Evaluation Of The Generated Geometrical Topography In Diamond Turning Of Optical Freeform Surface

In the fields of energy, environment, military, aerospace, the demand for ultra-precision optical components is growing. Optical freeform surface which have special structure and a new optical design concept, with the advantage of maximum simplify the system structure, reduce costs, correct errors, improve image quality, expand the field and improve the performance of optical systems. Base on the outstanding feature of optical freeform surface, which has become the core of optical component on the new generation optical system. However, to design and machine an optical freeform surface is more difficult than a general spherical surface or an aspheric surface, because of its geometry complexity and particularity. All these have much circumscribed the wide use of the optical freeform surface. Therefore is the time to study the processing, testing the data of freeform surface optical. This thesis base on the data of topography of optical measurement, to guidance processing of high precision surface and to explore the reason of cause error for the optical freeform surface by analyzing the error surface.The thesis organic integrate wavelet analysis and power spectrum density analysis, in order to make sure the level of wavelet decomposition and reconstruct three-dimensional machined surface. It separate the error components from the surface accurately, reduce or inhibit the question that low frequency error components decomposition over, help to evaluation the form error. The thesis also discussed the problems of wavelet function selection, edge effect and the decomposition algorithm. Through analysis the generated topography in diamond turning of ideal optical freeform surface with wavelet method and extract the surface roughness error, verify the wavelet analysis of freeform surface topography is effective.The thesis used the one-dimensional and two-dimensional power spectrum density analysis method, analysis the error surfaces from the decomposition, especially the intermediate frequency and high frequency errors. The result revealed the effects of feed rate and nose radius on surface roughness error and showed surface roughness the distribution of spatial frequency and surface texture.The thesis constructed a data of machined composite surface topography, in order to verify the accuracy of wavelet analysis and the effect of wavelet function for the decomposition of errors. The results show that:the errors components from the wavelet analysis meet the assessment requirements; the choice of wavelet functions effect the accuracy of different frequencies error components decomposition, coif5 is the best wavelet function to separate freeform surface.The thesis provided the references for the evaluation of the generated topography in diamond turning of optical freeform surface. It help to promote the wide use of optical freeform surface in actual production.