摘要
在宽光谱膜厚监控系统中,利用光栅光谱仪分光,线阵CCD接收,完成光谱的一次性快速扫描来控制膜层厚度,达到实时监控的要求。而系统光谱扫描的准确性,直接影响膜厚实时监控的有效性。为了得到准确的光谱信息,首先确定CCD像素和光波波长的对应关系,基于特征谱线的离散关系,采用最小二乘拟合法建立了光谱标定函数,经实验,标定波长均方根误差为0.037nm;对于CCD实时输出的光谱监控信号,利用小波阈值优化算法抑制信号中的随机噪声,保留了光谱信号的细节成分,峰值误差的最大值为1.0%,峰位误差的最大值为0.3%,满足了监控中光谱分辨率的要求。
In a thin-film thickness wideband monitoring system,a grating spectrometer is utilized to disperse spectrum and the linear CCD is used to quickly finish spectrum scanning to control the thin-film thickness,which satisfies the requirements of the real-time monitoring.However,the accuracy of spectrum scanning directly affects the availability of the thin-film thickness real-time monitoring.In order to obtain precise spectrum information,the corresponding relationship between CCD pixel and spectral wavelength was determined.Based on the discrete relationship between characteristic spectral lines and pixels,the spectrum calibration function was established using the least-square fitting method,and the root-mean-square error of calibrated wavelength was 0.037 nm by experiment.Then aiming at the spectral monitoring signal from CCD output in real-time,the wavelet threshold filtering optimization algorithm was applied to suppress the random noise and the spectrum signal details were well reserved,the maximums of peak error and peak location error were 1.0% and 0.3% respectively,which satisfied the spectral resolution requirements.
出处
《应用光学》
CAS
CSCD
北大核心
2011年第5期937-941,共5页
Journal of Applied Optics
基金
陕西省教育厅基金(03JC28)
关键词
光谱实时测量
膜层厚度
光谱标定
噪声处理
spectrum real-time measurement
thin-film thickness
spectrum calibration
noise processing
