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Solving the input data in error correc-tion of optical fabrication by finite Fourier coefficient algorithm

Science china(Technological Sciences) 2006年第1期49卷 50-60页

作者： cheng haobo1,2. sun guozheng3.& feng zhijing2.1. department of optical engineering, Beijing {2. of Technology, Beijing 100081, china 2. department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, china 3. china North Industries Group Corporation, Beijing 100089, china 1. department of optical {2. Beijing Institute of Technology Beijing 100081 China 2. department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China 3. china North Industries Group Corporation Beijing 100089 China

A free-form lens (FFL) is a special surface that is difficult to be fabricated. FFL are usually fabricated by computer-controlled optical surfacing (CCOS) technique. During CCOS, the material removal amount is determined by the unit removal function (URF) convoluting with the input data――the dwell time. When the removal amount and the URF are known, how to solve the input data involves the special algorithm――deconvolution. Usually, the input data are solved by virtue of low pass filter or iterative methods. However, an approximation solution would destroy the machining stability nec-essary to perform precisely CCOS. In this paper, to solve the input data, a new method that is based on the finite Fourier coefficient is put forward. It can give a continuous and accurate solution for fabricating choice. Several parameters are simulated, which influ-ence the process of CCOS, and evaluating on the effect of the method is also carried out. Experimental results verify that this method is suitable for guiding the manufacturing of high precision FFL.

关键词： optical fabrication, computer controlled optical surfacing, free-form lens, finite Fourier coefficient, error correction.

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Micro-phenomenon and viscosity features of magnetorheological fluids at external field

Micro-phenomenon and viscosity features of magnetorheologica...

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2.d International Symposium on Advanced optical Manufacturing and Testing Technologies

作者： cheng haobo, {2. guozheng, feng zhijing, WANG Yongtian Dept. of optical engineering, Beijing institute of Technology, Beijing, china, 100081 Dept. of Precision Instruments and Mechanology, Tsinghua University, Beijing, china, 100084 china NORTH Industries Group Corporation, Beijing, china, 100089

Magnetorheological finishing (MRF) is a technique in which a magnetic-field stiffened ribbon of MR fluid is used to polish a workpiece. MR fluids are essentially suspensions of magnetizable particles immersed in a nonmagnetic fluid. These complex fluids show a unique ability to undergo rapid, nearly completely reversible, significant changes in their mechanical and optical properties upon application of an external magnetic field. The aim of this work is essentially to investigate the effect of microstructure and viscosity behavior of magnetorheological suspensions under the external electro-magnetic field. A viscometer equipped with a circular shape electro-magnetic coil around the testing tube is used. The viscosity of the MR fluids is experimentally studied with the change of the magnetic density. The microstructure and behavior of bending chains in MR fluids are observed by applying an electro-magnetic field,

关键词： Magnetorheological Finishing Magnetic Particles Viscosity

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