双光束镀膜系统中的信号优化处理研究

双光束镀膜系统中的信号优化处理研究
/ X" w0 H- N5 b# l) i2 f许世军[1,2] 任小玲[3][1]西安工业大学数理系,西安710032 [2]西安交通大学理学院,西安710049 [3]西安工程大学计算机学院,西安710048摘　要:为提高光电极值法膜厚监控质量，对微弱光电探测信号设计一套优化的电路处理和数字处理系统。基于双光束镀膜监控思想，提出三级模拟放大电路、双锁相对称放大电路、综合抗干扰技术、数字除法、防脉冲干扰数字滤波、数码显示线性化、剔除奇异数据和ΔR值极值判断等信号综合处理方案。实验表明：电路的测试路输出和参考路输出信噪比均大于500，漂移率≤7％／h；数码显示对反射率响应的灵敏度在整个反射率范围内均比较大，数码显示值的线性回归系数为0．979，低反射率膜的反射率显示分辨极限为0．02％；镀膜中极值点监控信号的不确定度至少比通用系统降低1个数量级，漂移率接近于0。采用此方案对微弱膜厚信号的高精度、高稳定性检测大大提高了膜厚监控系统的静态、动态稳定性和膜厚控制精度，膜厚控制的标准偏差为0．55％。[著者文摘]

$ e/ r* B1 A# M关键词:光学薄膜 信号优化处理 双锁相电路 复合滤波 双光束 精度
; X: z; f( E! T/ Q2 {; e0 g分类号:　TM932 O484.5[著者标引]文献标识码：A文章编号：1672-7126（2007）03-230-06栏目信息：技术交流
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Optimization of Signal Processing in Dual-Light Beams Film Thickness Monitoring SystemXu Shijun, Ren Xiaoling 1. Department of Mathematics ＆ Physics, Xi＇an Technological University, Xi＇an 710032, China ; 2. School of Science, Xi＇an Jiaotong University, Xi＇an 710049, China ; 3. School of Computer, Xi＇an Polytechnic University, Xi＇an 710048, China Abstract:A novel technique has been successfully developed by optimizing the circuitry and data processing to improve precision of photoelectricity-extremum thin-film thickness monitoring（TFTM）. Based on the film-thickness monitoring of daul-light beams TFrM, the new technique involves analog circuits of multi-stage amplifier, symmetrical dual-lock-phase amplifier, anti-disturbance circuit technique, digital division, filters shielded from digital pulse disturbance,linearization of nixie display,singular data removal, and extremum judgment with ΔR algorithm. Results show that the analog signal-to-noise ratios of reference path and measurement path are more than 500, that the static drift ratios of two output signals are equal to or less than 7 %/h. In all reflectivity scope, the nixie display sensitivity responding to reflectivity is higher, the linear regression factor of nixie display data is 0.979, and the display resolution of low reflectivity is equal to 0.02 %. Experiments obtain that the uncertainty of monitoring signal declines one order of magnitude compared with the conventional TFTM system, that the drift ratio of monitoring signal approaches zero. The experimental results show that the new technique reduces the standard deviation control of the thickness to iess than 0.55 %. Its many advantages over the conventional technique include higher stability and better precision in static and/or dynamic controlling of the film thickness.[著者文摘]
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Key words:Optical thin-film, Signal optimum processing, Dual-lock-phase circuit, Compound fihemtion, Dual-light beams, PreCision