透明薄膜的干涉相干峰分离算法

白光干涉技术具有高度唯一性,广泛地被使用在三维表面形貌和台阶高度的测量。但是测量透明薄膜时,薄膜表面和基面都有光线反射与参考光线交汇,在被测表面的同一个位置不同高度两次产生干涉条纹,其干涉相干图中出现两个峰值。通过分析透明薄膜产生的干涉相干图的特点,提出了两种算法用来分离不同表面产生的干涉条纹。理论分析和试验结果表明,利用垂直扫描白光干涉法测量透明薄膜,由峰值分离算法和定位算法分别提取薄膜的上下表面,能够得到透明薄膜的高精度三维形貌和厚度信息。

Correlogram peak separate algorithms of transparent film

Because of its theoretically unlimited unambiguous height range and high-precise,the white-light interferometry is widely employed in the measurement of surface profile.While a transparent film is measured,because two beam of lights come from transparent film surface and substrate interfere with the reference light,interference fringe appears twice at the same point and two coherence-peaks are found in the correlogram.The characteristic of correlogram come from transparent film is analyzed and two algorithms are presented to separate the of interference fringes from two difference surfaces.Theoretical analysis and experiment result show that three dimensional surface and thickness distribution of transparent film measured by white-light interference microscope have high precision when the two coherence peaks at film surface and film substrate are efficiently separated by algorithms.