Measurement of DOE's 3-D surface profile based on two-wavelength phase-shifting interferometry and data analysis

The paper describes a new three-dimensional surface profile measuring method based on two-wavelength phase-shifting interferometry (PSI) and data analysis, which can be applied to measure the 3-D surface profile of a continuous type diffraction optical element (DOE) as well as a discontinuous type DOE. With the method a new measuring system is set up. The depth resolution is 0.5nm, the depth measuring range is 1.5 mu m (when two-wavelenth measurement method of lambda(1)=0.6 mu m, lambda(2)=0.5 mu m is adopted), the depth measuring accuracy is better than 1.3nm. This basically fulfills the demand for surface profile measurement of DOE.