Research On Metrology Platform And Parameters Evaluation In Surface Topography Measurement

3D surface topography evaluation could offer the information from some surface regions, and give the intuitionistic image of measured surface. More information about the process of producing surface could be obtained by 3D surface topography evaluation. It can supply more real and full-scale information about the surface of part and represent the function speciality. However, before evaluation of 3D surface topography, the data about 3D surface topography must be obtained firstly. When measuring the roughness, only the precision of vertical direction must be ensured. While measuring in 3D profile, the precision of vertical direction must be assured too. At the same time, the precision of horizontal X-Y direction is also made sure. Therefore, in this thesis, X-Y platform of metrology is researched. It could satisfy the requirement of precision in 3D surface topography measurement. And it also could be used in to position the coordinates of X and Y direction of the touching surface profile measuring instrument and white interference vertical scan surface profile measuring instrument. After obtaining the 3D surface profile, it is difficult to define and compute the 3D parameters dues to the complexity of surface topography. Therefore, in this thesis, the 3D evaluation parameters had been computed in detail referring to the International Standardization standard in 3D measurement. The arithmetic of 3D parameters is also optimized in this thesis. The main contents and results of this thesis are as follows:1. Acting metrology grating as a regulator, the metrology X-Y platform has been developed. The principle of platform to work has been studied, and the elements to constitute the platform are also introduced. At the same time, the key techniques of the platform are analyzed in detail and the system is controlled with closed loop. The max range of the X-Y platform is 50mm×50mm and the resolution of position is prior to 1μm.2. The circuits to discern direction,subdivide and count the grating signal with Moir's fringe are designed and the software to compensate is also developed. The position resolution of grating is prior to 1μm.3. Referring to the International Standardization in 3D measurement, the 3D evaluation parameters have been computed in detail. The arithmetic of 3D parameters is also optimized. The error has been analyzed. The computed results have been compared with the international authority's.4. The 3D simulating model has been built based on OpenGL, and the model has been compared with the model based on grid. The model offers more information about measured surface. Contrary to grid model, the OpenGL model is more three-dimensional,visual and convenient to treat.5. The application programming interface has been developed with Borland C++ Builder(BCB). The software can be used to control the X-Y platform, simulate the 3D surface profile and evaluate the 3D surface parameters.6. The position precision has been validated by test. And, the reliability of arithmetic of 3D parameters is also confirmed in the thesis.