Multi-mode interferometric measurement system based on wavelength modulation and active vibration resistance

Optical interferometers are widely used in the measurement of micro- and nanoscale surface topography. However, their accuracy and resolution can be seriously affected by environmental noise. We present a multi-mode interferometric measurement system based on wavelength modulation and active vibration resistance. This supports two measurement modes: wavelength-scanning interferometry, which is suitable fbr structured surfaces, and wavelength-tuning interferometry, which is suitable for smooth continuous surfaces. In addition, the system can measure the optical path difference of the current position in real time, which is convenient for making system adjustments and improving the measurement accuracy. The proposed system was used to measure 1.806 mu m and 43.2 nm step height standards. Under different degrees of vibration, the measured heights in the two modes agreed well with the calibrated values. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement