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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。
The traditional five-step algorithm has good accuracy, but must meet the conditions of equal-step phase shift that can not be achieved in the measurement, which can not be used in the actual measurement. Based on the theory of double-beam interference, an improved five-step algorithm is proposed to achieve the high accuracy of the algorithm with arbitrary step in the range of 10 nm. The numerical simulation results show that the algorithm accuracy of the improved five-step algorithm is better than 0.001 phase period for 1-nm step measurement error and 0.1% signal measurement error, and does not require equal-step phase shift control. The improved five-step algorithm is not only technically easier to implement, the result is more reliable, which is of great significance for the experiment and research to guide the precision measurement.