In order to restrain the mid-spatial frequency error in magnetorheological finishing (MRF) process, a novel part-random path is designed based on the theory of maximum entropy method (MEM). Using KDMRF-1000F polishing...In order to restrain the mid-spatial frequency error in magnetorheological finishing (MRF) process, a novel part-random path is designed based on the theory of maximum entropy method (MEM). Using KDMRF-1000F polishing machine, one flat work piece (98 mm in diameter) is polished. The mid-spatial frequency error in the region using part-random path is much lower than that by using common raster path. After one MRF iteration (7.46 min), peak-to-valley (PV) is 0.062 wave (1 wave =632.8 nm), root-mean-square (RMS) is 0.010 wave and no obvious mid-spatial frequency error is found. The result shows that the part-random path is a novel path, which results in a high form accuracy and low mid-spatial frequency error in MRF process.展开更多
Computer-controlled sub-aperture polishing technology is crucial for achieving high-precision optical components.However,this convolution material removal method introduces a significant number of mid-spatial frequenc...Computer-controlled sub-aperture polishing technology is crucial for achieving high-precision optical components.However,this convolution material removal method introduces a significant number of mid-spatial frequency(MSF)errors,which adversely impact the performance of optical systems.To address this issue,we propose a novel controllable spiral magnetorheological finishing(CSMRF)method that disrupts the mechanism of conventional constant tool influence function(TIF)convolution material removal.In this study,we leverage the advantages of a time-varying spacing strategy and theoretically analyse how time-varying spacing,combined with the spiral swing process of the TIF,mitigates MSF ripple errors.The time-varying spacing method highlights the importance of controlling the characteristic frequency,while the CSMRF method demonstrates a smoothing effect on the errors within the MSF band.Our findings confirm that time-varying spacing and spiral swinging have complementary effects in managing MSF errors.Furthermore,by constraining the MSF error and specific frequency error,we identify the optimal combination of adaptive spacing and spiral angle using a genetic algorithm.On this basis,the MSF error is evaluated by combining the characteristic dwell time solution algorithm.Using the inertial confinement fusion optical element as an example,we observe a 99.938%reduction in the amplitude of the PSD curve of the mid-frequency ripple error with a spatial period of 1 mm,while the mid-frequency PSD curve remains within the standard line.Therefore,the proposed method can effectively control the specific MSF error distribution.This variable convolution kernel(TIF)sub-aperture polishing method provides a new idea for full-band cooperative error control.展开更多
为实现高效率、低成本的镍磷合金光学元件全频段误差抑制,提出了小磨头抛光中基于宏观耕犁机制和微观化学键拔除机制的宏微观协同作用去除机理。基于赫兹接触理论,通过工件表面的弹塑性形变探讨耕犁机制产生的临界值,构建了磨粒作用机...为实现高效率、低成本的镍磷合金光学元件全频段误差抑制,提出了小磨头抛光中基于宏观耕犁机制和微观化学键拔除机制的宏微观协同作用去除机理。基于赫兹接触理论,通过工件表面的弹塑性形变探讨耕犁机制产生的临界值,构建了磨粒作用机制与工艺参数之间的关联模型——小磨头抛光磨头极限压力模型,实现了对宏微观去除机制的调控,从而达成全频段误差的有效抑制。随后通过第一性原理分子动力学仿真分析,探究了抛光过程中磨粒分子团簇与镍磷合金光学元件表层分子的相互作用,直观表征了镍磷合金抛光过程中的微观化学键拔除机制,该仿真分析对镍磷合金光学元件超光滑抛光具有指导意义。基于宏微观协同作用去除机理对φ50的铝基镀镍磷合金平面反射镜进行小磨头迭代抛光实验,在有效抑制中低频误差的同时,将表面粗糙度R a从2.252 n m提升到0.502 nm,提升了77.7%,实现了镍磷合金反射镜超光滑表面全频段误差的抑制。实验结果表明,宏微观协同作用去除机理适用于镍磷合金光学元件的全频段误差抑制,对于镍磷合金光学元件超精密加工提供了借鉴意义。展开更多
单频网(Single Frequency Network,SFN)的运行对发射机的同步提出极高的技术要求,任何同步误差都可能对网络性能产生不利影响。首先分析SFN中时间、频率和相位同步误差的定义与分类,其次探讨其对关键性能指标的影响机理,并量化同步误差...单频网(Single Frequency Network,SFN)的运行对发射机的同步提出极高的技术要求,任何同步误差都可能对网络性能产生不利影响。首先分析SFN中时间、频率和相位同步误差的定义与分类,其次探讨其对关键性能指标的影响机理,并量化同步误差对覆盖范围和信道容量的削弱程度,最后针对同步误差的成因提出提高授时源精度、优化参考时钟选型、改进同步跟踪环路设计及多径信号抑制等策略。展开更多
基金Supported by the National Basic Research Program of Chinathe National Natural Science Foundation of China (Grant Nos. 61332, 50775215, 50875256)
文摘In order to restrain the mid-spatial frequency error in magnetorheological finishing (MRF) process, a novel part-random path is designed based on the theory of maximum entropy method (MEM). Using KDMRF-1000F polishing machine, one flat work piece (98 mm in diameter) is polished. The mid-spatial frequency error in the region using part-random path is much lower than that by using common raster path. After one MRF iteration (7.46 min), peak-to-valley (PV) is 0.062 wave (1 wave =632.8 nm), root-mean-square (RMS) is 0.010 wave and no obvious mid-spatial frequency error is found. The result shows that the part-random path is a novel path, which results in a high form accuracy and low mid-spatial frequency error in MRF process.
基金funded by the National Natural Science Foundation of China(62175259)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA25020317)+3 种基金Science and Technology Innovation Program of Hunan Province(2022RC1138)Science and Technology Innovation Program of Hunan Province(2023JJ30079)Science and Technology Innovation Program of Hunan Province(2024JJ6460)Graduate Science and Technology Innovation Project of Hunan Prov.(CX20230019).
文摘Computer-controlled sub-aperture polishing technology is crucial for achieving high-precision optical components.However,this convolution material removal method introduces a significant number of mid-spatial frequency(MSF)errors,which adversely impact the performance of optical systems.To address this issue,we propose a novel controllable spiral magnetorheological finishing(CSMRF)method that disrupts the mechanism of conventional constant tool influence function(TIF)convolution material removal.In this study,we leverage the advantages of a time-varying spacing strategy and theoretically analyse how time-varying spacing,combined with the spiral swing process of the TIF,mitigates MSF ripple errors.The time-varying spacing method highlights the importance of controlling the characteristic frequency,while the CSMRF method demonstrates a smoothing effect on the errors within the MSF band.Our findings confirm that time-varying spacing and spiral swinging have complementary effects in managing MSF errors.Furthermore,by constraining the MSF error and specific frequency error,we identify the optimal combination of adaptive spacing and spiral angle using a genetic algorithm.On this basis,the MSF error is evaluated by combining the characteristic dwell time solution algorithm.Using the inertial confinement fusion optical element as an example,we observe a 99.938%reduction in the amplitude of the PSD curve of the mid-frequency ripple error with a spatial period of 1 mm,while the mid-frequency PSD curve remains within the standard line.Therefore,the proposed method can effectively control the specific MSF error distribution.This variable convolution kernel(TIF)sub-aperture polishing method provides a new idea for full-band cooperative error control.
文摘为实现高效率、低成本的镍磷合金光学元件全频段误差抑制,提出了小磨头抛光中基于宏观耕犁机制和微观化学键拔除机制的宏微观协同作用去除机理。基于赫兹接触理论,通过工件表面的弹塑性形变探讨耕犁机制产生的临界值,构建了磨粒作用机制与工艺参数之间的关联模型——小磨头抛光磨头极限压力模型,实现了对宏微观去除机制的调控,从而达成全频段误差的有效抑制。随后通过第一性原理分子动力学仿真分析,探究了抛光过程中磨粒分子团簇与镍磷合金光学元件表层分子的相互作用,直观表征了镍磷合金抛光过程中的微观化学键拔除机制,该仿真分析对镍磷合金光学元件超光滑抛光具有指导意义。基于宏微观协同作用去除机理对φ50的铝基镀镍磷合金平面反射镜进行小磨头迭代抛光实验,在有效抑制中低频误差的同时,将表面粗糙度R a从2.252 n m提升到0.502 nm,提升了77.7%,实现了镍磷合金反射镜超光滑表面全频段误差的抑制。实验结果表明,宏微观协同作用去除机理适用于镍磷合金光学元件的全频段误差抑制,对于镍磷合金光学元件超精密加工提供了借鉴意义。
文摘单频网(Single Frequency Network,SFN)的运行对发射机的同步提出极高的技术要求,任何同步误差都可能对网络性能产生不利影响。首先分析SFN中时间、频率和相位同步误差的定义与分类,其次探讨其对关键性能指标的影响机理,并量化同步误差对覆盖范围和信道容量的削弱程度,最后针对同步误差的成因提出提高授时源精度、优化参考时钟选型、改进同步跟踪环路设计及多径信号抑制等策略。
