Simultaneous dual-wavelength phase-shifting interferometry for surface topography measurement

To deal with vibration disturbance in interferometric measurement of surface topography, we present a simultaneous dual-wavelength phase-shifting interferometry (SDWPSI). SDWPSI collects phase-shifting interferograms of two wavelengths simultaneously with two cameras to accelerate data collection. The optical phases are retrieved from dual-wavelength interferograms with an iterative algorithm that is tolerant of phase-shifting error caused by vibration. And then the measured surface topography is reconstructed by fusing the phases of two wavelengths. Simulations and experiments verify that SDWPSI has a lower measurement noise than single-wavelength interferometry and extends the discontinuity limit to several micrometres. SDWPSI has advantages of high speed, vibration resistance, and low cost, and could be applied to in-workshop and on-machine measurement.