Investigation of common-path interference profilometry

The principle of laser common-path interference profilometry based on the theory of Gaussian beams is analyzed and its measure- ment equation is deduced. From the measurement equation, the main factors that affect the vertical resolution of the profilometer are dis- cussed. According to the conclusions of the analysis, laser common-path interference profilometry can be used to measure microprofiles of fine surfaces with subnanometer vertical resolution.