Digital-micromirror-device-based surface measurement using heterodyne interferometry with optical frequency comb

We propose a surface measurement method based on optical frequency comb heterodyne interferometry ranging. A digital micromirror device is used to establish a single-pixel detection system without a mechanical scanning device and realize high-speed sampling. The measurement range of the step height is extended by synthetic wavelength interferometry from half of the carrier wavelength to half of the synthetic wavelength (40 μm in this system). Thus, a sample composed of three gauge blocks and an MEMS device of the teardrop-shaped groove were measured with an accuracy of 5 nm and a measurement time of 27 ms.