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为了实现光学元件的高精度加工,对离子束加工过程中关键的驻留时间求解算法进行了研究。通过分析离子束加工过程的基本原理,将传统的驻留时间反卷积求解过程转化为求解矩阵方程过程。在将正则化加权因子引入矩阵方程的基础上,又引入额外加工余量这一新的参量,增加了解的自由度,从而扩大了驻留时间解的搜索范围,同时将Gerchberg带限外插算法应用于初始面形的优化延拓中,保证了全孔径范围内面形精度一致。实例计算50mm的平面光学元件表明,面形精度从初始的均方根值为0.5747λ,峰谷值为2.3706λ(λ=632.8nm)收敛到全孔径范围内的均方根值为0.001λ,峰谷值为0.0115λ。由此可见该优化求解过程可有效地求解出驻留时间,为离子束加工过程提供了有力的保障。
In order to achieve high-precision machining of optical components, algorithms for solving the critical dwell time in ion beam machining have been studied. By analyzing the basic principle of ion beam processing, the traditional deconvolution solution of dwell time is transformed into the process of solving matrix equation. Based on introducing the regularization weighting factor into the matrix equation, the new parameter of extra machining allowance is introduced to increase the degree of freedom of understanding, so the search range of dwell time solution is expanded. At the same time, the Gerchberg band limited extrapolation method Applied to the optimization of the initial surface extension, to ensure that the entire aperture range of surface accuracy consistent. An example calculation of a planar optical element with a diameter of 50 mm showed that the surface shape accuracy was improved from an initial rms value of 0.5747λ and a peak-to-valley value of 2.3706λ (λ = 632.8 nm) to a full-aperture rms value of 0.001λ , The peak value is 0.0115λ. This shows that the optimal solution process can effectively solve the dwell time, which provides a powerful guarantee for the ion beam processing.