用于纳米测量的混合型外差干涉信号处理方法

Hybrid processing method of heterodyne interferometer signal for nanometrology

通过对外差干涉信号同时进行相位检测和锁相倍频计数，可得到存在一定冗余度的一组测量结果，经过一定的逻辑混合；可实观测量分辨率优于０．１ｎｍ，测量范围不受λ／２周期限制，从而克服了以往单一采用相位测量法测量范围限于一个周期和锁相倍频计数法分辨率不易提高的难题。给出了在实际纳米测量干涉仪采用这种外差信号处理方法的测量结果。

A hybrid processing method, which combines the traditional phase measurement method for inner period measurement and phase locked frequencymultiply counting method for integer periods measurement, is described. This method can achieve high resolution of 0 1nm with measuring range been enlarged. Avoid the limitation of measuring range or resolution lie in the above two traditional processing method. By introducing a acceptable redundant measurement, the integer period can be measured correctly despite of the errors may exist in counting circuit. The combination rule is described in detail. This method is adopted in a novel nanometrology interferometer, the experiment result supports the above analysis.