Development Of Micro-displacement Precision Platform Equipped With Metrology System

The measurement and characterization of 3D surface topography is representative of a primary development direction of surface metrology. Nowadays, microscopy interferometry has become one of main measuring techniques of 2D profile and 3D topography. Compared to other measuring techniques, microscopy interferometry not only has many advantages such as high measurement accuracy and visualized surface information, but also can measure surface topography of an area at a time. Scanning white-light interferometry (SWLI) is a relative new method in microscopy interferometry. It can measure discontinuous surface, which overcomes many of the limitations of conventional phase-shifting interferomtry (PSI) with a single-wavelength because of the cyclic nature of the interference. The problem that the measuring surface discontinuities are not able to be greater than half a wavelength in PSI with a single-wavelength can be resolved effectively, and the measuring range can be extended dramatically. In our country, the research in this realm is still in the initial stage, and the mature product has not been developed. The micro-displacement precision platform equipped with metrology system developed in this dissertation, as one of the key techniques, will lay the technique foundations for development of the 3D topography profilometer based on vertical scanning white-light interferomtry. The main research contents in this dissertation are as follows: The design scheme of the 3D surface profilometer based on scanning white-light interferometry is presented. The structure of the micro-displacement precision platform equipped with metrology system is designed. The characteristics of white-light interference, the measuring and working principle of the profilometer, and the key techniques are analyzed. According to the grating interference principle, the optical system of the platform is designed, and the metrology principle is deduced in detail. The measuring error is analyzed from two aspects of grating manufacture and grating position variation. Aiming at the characteristics of the precision platform, the photoelectric conversion and preamplification circuit, the direction distinguishing and signal subdivision circuit, and the driving power for piezoelectric actuator are designed. At the same time, the theoretical analysis method of photoelectric detection is studied. For the new method of photoelectric diode array placement, the theoretical certification is given. For the non-orthogonal signals from photoelectric conversion, the amending method is explained. The virtual instrument technology is introduced in the precision platform, and the user program is designed. Making use of the function of the precision platform, the measuring experiments of 3D surface topography of the standard template are accomplished by the profilometer, which meet with the initial success. The coarse adjustment stroke of the platform is 1mm, the precision adjustment stroke is 16μm, and the vertical resolution is 1nm.