Precision Surface Profile Measurements by Comb-based Multi-wavelength Interferometry,

Abstract

Precision measurement of large-stepped surface profiles is demonstrated using the frequency comb of a femtosecond pulse laser. Four optical wavelengths are selected out of the frequency comb to realize the principle of multi-wavelength interferometry with traceability to the Rb atomic clock of time/frequency standard. A large step-height of ~70 μm is exemplarily measured with nanometre precision with the maximum measurable height being extended to tens of mm.