Interferometric Surface Profile Measurement Based on Radial Polarization and Wavelength Variation

A radial-polarization-based interferometric method is proposed for measuring object surface profiles. In the proposed approach, a radially polarized beam is generated by transmitting a linearly polarized beam through a zero-order vortex half-wave plate and is then introduced into a modified Twyman–Green interferometer, in which the test specimen is placed in one interferometric arm. By introducing a small variation in the wavelength illumination, two interferometric intensity patterns are recorded using a CMOS camera. The corresponding phase difference distribution is retrieved from the recorded intensities and subsequently used to reconstruct the surface profile of the specimen. The feasibility of the proposed method is experimentally validated by measuring a convex mirror, and the results show good agreement with theoretical predictions. Owing to its simple optical configuration, ease of alignment, high measurement accuracy, and rapid measurement capability, the proposed method demonstrates strong potential for practical surface profile measurement applications.