Research Advances in Multiple-Measurement Technology Using Nanometer Time-grating Sensors
Engineering Research Center of Mechanical Testing Technology and Equipment (Ministry of Education), Chongqing University of Technology, Chongqing, China.
Nanometer displacement measurement technology and its associated displacement sensors are the key technology and vital functional parts for the ultra-precision high-end equipment, such as the high-end NC machine tools, special equipment of VLSI, and serve as an eye function for the high accuracy positioning and control. Therefore, the performance of the positioning systems is mainly determined by the measuring accuracy of the displacement sensors. However, with the development of measurement accuracy, there are three key challenges, i.e. contradiction between measuring range and measuring accuracy, errors tracing to the source with the increasing improvement of measurement accuracy, and how to overcome diffraction limit and improve measurement resolution, which limit the further development of nanometer displacement measurement technology. Aiming at above-mentioned three key challenges, an original academic thought named a nanometer time-grating displacement measurement method was firstly proposed, and its principle is to built a highly stable motion serving as a time reference, with which the high precision displacement measurements are implemented using time comparison techniques. The proposed nanometer time-grating academic thought completely differs from the traditional displacement measurement method which needs to fabricate an ultra-precise equivalent graduated scale as spatial reference standards, with which the target positions are measured using spatial position comparison techniques. After 20 years of hard work, a set of more systematic nanometer time-grating measurement theory has been built up. The highlights of measurement principles of nanometer time-grating sensors are independent of ultraprecision and dense machining of the grating line for the measurement performance improvement of the traditional existing displacement sensors. Therefore, the nanometer time-grating sensors are essentially independent of the fabricating machinery for large-size micro-nano machining, which provides a novel thought completely differing from the existing technology at home and abroad for achieving the goals of nanometer measurement accuracy with higher resolution over the measurement range of hundreds micrometers or even more. A pioneering exploration and research about nanometer time-grating sensors will be reported briefly in the last.
Prof. Xiaokang Liu is dean of College of Mechanical Engineering, and director of Engineering Research Center of Mechanical Testing Technology and Equipment (Ministry of Education), Chongqing University of Technology, Chongqing, China. He received the B.E., M.E. and the PhD. degrees in mechanical and electronic engineering from Chongqing University in 1999, 2002 and 2005, respectively. He worked as a postdoctor of instrumentation science and technology in Hefei University of Technology from 2006, and moved to Chongqing University of Technology in 2008. And since 2009, as a project leader, he has been responsible for more than 30 research programs including 2 key programs supported by the National Natural Science Foundation of China (NSFC). He has published more than 60 technical papers in peer-reviewed journals, and 22 invention patents including 6 international PCT patents. He received National Award for Technological Invention 2nd Prize in 2010, Gold Award for Outstanding Chinese Patented Invention in 2008 and two Chongqing Award for Technological Invention 1st Prize in 2006 and 2021, respectively. His research activity mainly includes micro-nano sensing theory and technology, mechatronic system and intelligent instrumentation. As the first inventor of the nanometer time-grating displacement sensors, he is currently involved in a key program of NSFC for the development of next generation national angular metrology standard using nanometer time-grating displacement sensors.