A Novel 3D Profilometer Based on Linear Phase Grating Interference

The nature of the surface topography significantly influences its functional performances, such as the lubrication, wear, friction, corrosion, fatigue, et al. Therefore, the need for accurate surface metrology is becoming more and more important. This paper introduces a high-precision 3D profilometer for surface metrology with the characteristic of high resolution, long measure range and low cost. The 3D profilometer consists of several parts: the micro-displacement sensor based on linear phase grating interference, the X-Y 2D platform, the column, the optoelectronic detector and its signal processing circuit, the computer and data processing software. The precise linear motion of the displacement sensor is implemented by parallel springs and its high precise displacement measurement is realized by sine phase diffraction grating. The theoretical vertical resolution of the micro-displacement sensor may achieve 0.12 nm, and the actual measuring range of the displacement sensor is 2mm, which can reach 6mm by replacing the measuring lever. The 2D platform is driven by servo motor and the double diffraction grating metrology system is adopted to measure the position of the platform. The resolution step displacement of the 2D platform is 0.2um.