纳米级微间距的多波长干涉测量方法

多波长干涉测量法适用于纳米级微间距的实时动态非接触测量.纳米级间隙之间的空气形成一层具有光学特性的空气薄膜.该空气薄膜的光强反射率是关于入射光波长和薄膜厚度的函数.在多波长干涉法中,以包含多种波长的复合入射光照射薄膜,入射光被空气薄膜分成2部分,一部分穿过薄膜,另一部分则被反射回来.利用一种特殊的方法测得该薄膜的光强反射率,进而根据薄膜厚度与入射光波长和相应的光强反射率之间的函数关系建立方程组.通过对方程组求解,计算出薄膜的厚度.多波长干涉测量法能够避免移相干涉法中移相器所带来的误差,并且可根据不同波长的光波测出的结果相互校正,提高了测量精度.通过实验对多波长干涉测量法进行了验证,实验结果充分证明了系统设计及理论依据的正确性.

Multi-wavelength interferometry for nanometer scale spacing

The multi-wavelength interferometry can be used for real-time and untouched measurement for nanometer scale spacing.The air stuffed in the small spacing forms a thin film.The intensity reflectivity of the film is correlated with the wavelength of an incident ray and the height of the film.In multi-wavelength interferometry,incident rays with several wavelengths direct through the film and are divided into two portions.One portion passes through the film,another reflects from the film.The intensity reflectivities are measured by a special means according to the wavelengths.With the reflectivities and known wavelengths,the film height can be calculated out from an equations set based on the correlation of film height,wavelengths of the incident rays and intensity reflectivities of the film.Multi-wavelength interferometry avoids the error caused by phase shifter in phase-shifting interferometry,and the final measurement result can be corrected by measurement results from different wavelengths,therefore,the precise is improved.An experiment for the multi-wavelength interferometry is carried out,and the results fully demonstrate the correctness of system and theoretical basis.