Real-time Thickness Measurement with a Modified Sagnac Interferometer Using Phase Shift Technique

The modified Sagnac interferometer with a phase-shift approach is given here for measuring Ta2O5 thin-film thickness. The input light is split into reference and sample beams. A real-time signal measurement is performed to get the output intensities of both beams with four different polarizer settings. These intensities can then be effectively converted into film thickness.