光学元件抛光的PSD分析及控制策略

PSD analysis and control strategy of optical component polishing

在光学加工领域,采用功率谱密度(power spectral density,PSD)对误差频谱方面信息进行表征,但是功率谱密度是表面误差统计信息,不如峰谷值(peak-valley,PV)和均方根值(root mean square,RMS)直观。为了分析功率谱密度与工艺参数之间的关系,该文从PSD定义出发,分析了随机面形轮廓不同参数对光学PSD的影响规律,总结了PSD控制的要点,在平面玻璃上对数控抛光典型路径下加工的PSD曲线进行分析。分析结果表明:PSD与随机轮廓幅值、频率分布有关,相位对它几乎无影响;在RMS接近情况下,PSD线性拟合斜率和RMS Slope随随机轮廓的自相关长度增加而下降;短程加工路径相较于长程有序路径能够有效抑制PSD曲线峰值,使得光学元件符合频谱抑制要求。

In the field of optical fabrication,the power spectral density(PSD)is used to characterize the error spectrum.However,the PSD is the statistical information of surface error,which is not as intuitive as peak-valley(PV)and root mean square(RMS).In order to analyze the relationship between PSD and process parameters,based on the definition of PSD,the influence of different parameters of random surface contour on optical PSD was analyzed,and summarized the key control points of PSD.Then,the PSD curves processed under the typical paths of numerical control polishing were analyzed on flat glass.The results show that the PSD is correlated with the amplitude and frequency distribution of random contour,and the phase has almost no influence on it.When the RMS is close,the slope of PSD linear fitting and RMS Slope decreases with the increase of the auto-correlation length of the random profile.The short-range machining path can effectively suppress the peak value of PSD curve compared with the long-range ordered path,which makes the optical element meet the requirements of spectrum suppression.