Surface profile measurement of transparent parallel plates by multi-scale analysis phase-shifting interferometry (MAPSI)

The application of wavelength-tuning interferometric techniques is vital in addressing measurement complexities related to surface profile errors in transparent parallel plates due to their non-contact nature and high precision. Traditional methods often impose strict interferometric cavity length requirements, leading to inherent complexities. To tackle these challenges, this paper proposes cavity length-independent Multi-scale Analysis Phaseshifting Interferometry (MAPSI), enhancing measurement flexibility and efficiency. MAPSI adjusts wavelength tuning and employs multi-scale analysis, addressing under-sampling and spectrum shifting while enabling precise frequency sampling, harmonic error suppression, and enhanced phase extraction. Experimentation on a 90 mm-aperture quartz parallel plate yielded surface profile errors with peak-to-valley (PV) and root-mean-square (RMS) values of 0.055 lambda and 0.012 lambda (lambda = 632.8 nm). Notably, MAPSI achieves lambda/100 (PV) precision with fewer interferogram samplings than Fourier transform phase-shifting interferometry (FTPSI). The results validate the MAPSI's consistency and applicability, underscoring its potential for widespread adoption in expedited optical shop testing processes, offering a novel solution for meticulous evaluation of surface profiles in transparent parallel optical components.