Author Affiliations
Abstract
National Institute of Metrology, Beijing 100013
Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to \pi/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming to overcome this defect of traditional five-interferogram algorithm, an improved five-interferogram algorithm is presented. This improved algorithm not only keeps the high accuracy of traditional five-interferogram algorithm, but also does not need absolute equal step to unwrap phase. Instead, this algorithm only needs measuring phase-shifting. With the numerical simulation, the improved five-interferogram algorithm shows high accuracy, high reliability, and feasibility in practice. It is very valuable for accurate length measurement with Fizeau interferometer and Fabry-Perot interferometer.
多光束干涉 五幅相依算法 精密测长 相位误差 120.3180 Interferometry 120.2650 Fringe analysis 120.2230 Fabry-Perot 120.3930 Metrological instrumentation 120.3940 Metrology Chinese Optics Letters
2008, 6(5): 342
传统五步算法具有很好的准确度,但必须满足测量中无法实现的等步长相移条件,这在实际测量中无法使用。为此在双光束干涉原理的基础上,提出了一种改进型的五步算法,实现了在10 nm范围内任意步长的算法高准确度。通过数值模拟,结果表明:对于1 nm的步长测量误差、0.1%的信号测量误差,改进型五步算法的算法准确度优于0.001个相位周期,而且不需要等步长相移控制。改进型五步算法不仅技术上更易于实现,其结果也更加可靠,对于指导精密测长的实验和研究工作具有十分重要的意义。
光学测量 相移算法 五步算法 精密测长 相位误差
针对相移算法中以双光束干涉为基础的余弦依赖算法的算法误差,以菲佐干涉仪精密测长为应用背景进行了研究。利用干涉光学的基本原理导出了在多束光干涉(经光学面多次反射、透射)的情况下干涉光强随相位分布的精确公式;通过数值分析得出了在给定参量条件下忽略次级反射光所引入的光强误差达到14.4%;对余弦依赖算法所引起的光强误差分别就四步算法、五步算法得出了不同的依赖关系:由于四步算法比五步算法对光强误差更为敏感,因而五步算法具有更高的准确度;对于两个反射面均具有较高反射率的情况,必须考虑算法误差;当测长准确度要求不太高时,在两个或至少其中一个反射面反射率较低的情况下可以忽略算法误差的影响。
光学测量 精密测长 多光束干涉 相移算法 余弦依赖