| Micro-structured surface of ultra-precision turning is widely used in clean energy, optical imaging and other fields. The integrity of the surface topography is significant to the improvement of the conversion efficiency of the power generation device and the quality of the optical system. For the measurement of processed micro-structured surface topography, the off-line testing equipment is generally adopted, but it can only achieve a small-scale measurement of micro-structured surface topography. Therefore, in this paper, to achieve micro-structured surface topography in place and a wide range of measurement, and further improve the quality of workpiece surface and production efficiency, a set of in-situ testing system for the ultra-precision lathe is developed.In order to achieve micro-structured surface topography in place and a large scale of measurement, in this paper, a vertical scanning white light interferometry system is build and research on the development of optical in-situ testing system for ultra-precision lathe, reconstruction of micro-structured 3D surface topography, stitching method for microstructured 3D surface topography, performance evaluation of in-situ testing system, in place stitching experiments of surface topography and other key issues are carried out. The main works of this paper are:According to the characteristics of micro-structured surface, a set of optical interference in-situ testing system is designed based on the ultra-precision lathe. On the basis of optical interference's condition, the hardware components and performance parameters of the system are determined. The system's driven control and image acquisition software are integrated by using VS2010. Compositing the hardware and software of interference system, the real-time data acquisition and storage of the microstructured surface interference image can be realized, and providing data support for the reconstruction of 3D surface topography.According to the difference of light source, the characteristics of monochromatic light phase shift interference and white light interference are analyzed. Based on the principle of optical interference, several common white light interference fringe peak extraction algorithm are established and analyzed. For the interference image data acquired by the system, the MATLAB software is used to filter processing and the program of peak extraction algorithms are written.Combined with ultra-precision lathe motion, the topography data acquisition mode and the errors generation in single stitching are determined. For the error of translation transform in single stitching, the problem of translation transform image registration is solved by using fast template matching method. And the registration accuracy of the fast template matching method and the extended phase correlation method are determined by using MATLAB software simulation. Through MATLAB simulation, 3D topography off-plane deviation is modified.The performance and accuracy of the in-situ testing system are evaluated through the use of micrometer scale trench calibrated by AFM. Based on the image edge detection technology, the size of the pixel is calibrated by using standard grids' focus image, and the single aperture field of view is determined. Establishing and comparing the radial line fitting equation obtained by profiler and micro-structured 3D topography reconstruction of the three-step phase shift method, the micro-structured topography's recovery accuracy of single aperture is evaluated. Combined with the precision motion of ultra-precision machine tool's guide rail and spindle, a large range and in-situ stitching experiment of micro-structured 3D topography is carried out. |
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