Measured element phase-shifting interferometry with a single piezoelectric transducer and low-friction workbench

Moving a large-aperture reference mirror (RM) with a significant weight through piezoelectric transducers (PZTs) for phase-shifting introduces considerable challenges and potential problems in conventional reference mirror phase-shifting interferometry (RMPSI). In this report, we present measured element phase-shifting interferometry (MEPSI), which provides an alternative approach for RMPSI without the restrictions of both the aperture and weight of the RM. The proposed MEPSI actuates a low-friction workbench with an ME on board by single PZT to realize high-accuracy phase-shifting, which is not affected by the aperture or the RM weight of. On this basis, a tilt-shift immune phase-shifting algorithm is further applied to restrain the influence of residual tilt-shift errors and other possible error sources on the measuring accuracy. Theoretical analysis and preliminary experiments indicate that the proposed MEPSI can achieve the same level of accuracy as RMPSI and a ZYGO interferometer, and the repeatability of MEPSI, which is not affected by the weight of the ME, is superior to 0.002 λ (PV). MEPSI solves the problems of phase-shifting with large-aperture and heavy-weight RM, thereby providing a simple and feasible alternative approach for conventional RMPSI with the same level of accuracy and with no phase-shift calibration.