Dual-mode snapshot interferometric system for on-machine metrology

For the first time, we present a dual-mode snapshot interferometric system for measuring both surface shape and surface roughness to meet the need for on-machine metrology in optical fabrication. Two different modes, interferometer mode and interference microscopy mode, are achieved using Linnik configuration. To realize snapshot measurement, a pixelated polarization camera is used to capture four phase-shifted interferograms simultaneously. We have demonstrated its performance for off-line metrology and on-machine metrology by mounting it on a diamond turning machine.