Laser interferometry is one of the most effective means to realize ultra-precision measurement and control and micro-nano scale measurement, and an important way to ensure the traceability of nanometer measurement. It is also an indispensable key metrology and testing technology to become a powerful measurement and manufacturing country.
Reporter learned that, in the key state science and technology projects “greatly scale integrated circuit manufacturing equipment and complete sets of technology” special (02), and special projects such as instrument of national natural science fund support, li yan, WeiHaoYun by tsinghua university, Wu Xuejian, Zhang Hong yuan, Zhang Jitao, shi-jie zhao, Zhu Minhao, Chloe, Ren Libing, Yang Honglei completed “high speed multiaxial high resolution lasaer pointer interference measurement technology and instruments” project, in view of the lithography mechanic pieces of ultra precision positioning, basic measurement of laser interferometer in measuring instrument and high-end applications, high dynamic, high resolution, across scales and traceable measurement requirements, such as the A series of key technical bottlenecks were broken through, and new measurement methods, systems and instruments were formed.
Recently, the project of “high velocity multi-axis high resolution laser interferometry technology and instrument” won the first prize of science and technology progress of China metrology and testing association in 2018.
Long affiliate professor of tsinghua university, the project leader precision instruments is li yan, director of the academic committee introduction, project implementation components, signal from the interferometer detection demodulation to multiple degrees of freedom the scheme design of the whole chain from research and development of high speed, multi-axis big range, high resolution laser interference measurement system, its remarkable characteristic is that: in view of the lithography for harsh environment realize multidimensional interference measurement requirements, based on prism error vector analysis of monomer component design method of integrated multi-axis interferometer developed from 2 to 5 axis series multi-axis interferometer component monomer type, break the monopoly of foreign enterprises and to our country’s export restrictions; Demand for high speed nanometer resolution interferometry, the author puts forward a kind of delay resolution whole decimal phase demodulation method and a kind of differential quadrature phase demodulation method based on digital frequency synthesis, developed a maximum speed of 2 m/s, 0.3 nm resolution, measurement range > 20 m, data uncertainty life < 1 ns multichannel interference signal demodulation module; A method of measuring the refractive index of equivalent synthetic wavelength chain gas using three vacuum tubes is presented, which compensates the refractive index of air and breaks through the limitation of the refractive index of air on the precision of optical interference measurement.
The project also proposed a precise measurement method of optical frequency traceable serialized laser interference, which mainly includes: develop a nonlinear traceable sub-nanometer traceable heterodyne interferometer with optical frequency traceable to meter, and realize heterodyne interference measurement with nonlinear error of 0.1nm; A laser output tuning control system of THz broadband and kHz frequency standard deviation with tracable optical frequency is established, and an integrated whole and decimal measurement method is proposed for optical frequency comb reference laser frequency scanning interferometry and interference phase measurement with arbitrary equal-frequency interval phase shift, so as to achieve high-precision absolute distance measurement. A tunable semiconductor laser resonance peak locking f-p interferometry system is proposed and established, which can directly convert the measurement of displacement change into the traceable measurement of output light frequency change. In principle, there is no non-linear, and the measurement ability of nanometer and absolute distance across the scale of PM is of quantitative significance.
It is reported that the above series of research results have been authorized invention patents more than 20, published SCI included papers more than 30, and as an important research achievements of tsinghua university was included in the “national 12th five-year science and technology innovation achievement exhibition”. The achievements enrich the theory and technology of laser interferometry, improve the performance index of interferometry, and expand the application field. The interferometer components and measuring system developed on the basis of this project research have been successfully applied and popularized in the fields of advanced equipment research and development, high-end scientific instrument development and scientific research.
So far, the project team of research and development of lithography with double-frequency laser interferometer system, successfully applied to the research in our country lithography mechanic in the process of research and development of a prototype, the cumulative application more than 50 sets, very good to satisfy the lithography double prototype workpiece precision measurement requirements, supporting the domestic printing machine with the formation of the dual-frequency laser interferometer ability, reduce the dependence on foreign high-end interferometer, reduces their products to our country export restrictions caused by the development risk, guarantee the lithography machine research and development, the smooth implementation of the double artifacts of the development of our country’s independent lithography mechanic platform plays an important role in technical support. The laser interference signal demodulation module formed by the key technological breakthrough of this project has been successfully applied to the domestic high-end instrument laser vibrometer, helping domestic enterprises to improve product performance and market competitiveness, and breaking the monopoly position of foreign companies in the international laser doppler vibrometer field. At present, the products have been successfully applied to aerospace, automobile manufacturing, machine tool testing and other fields, becoming a powerful support tool to improve the quality of products made in China.
Li yan said that the project research and the nanometer resolution traceable heterodyne interferometer, the successful application of the multidimensional measurement system research and development of laser alignment calibration study, find out the reason of the laser multidimensional nonlinear error measuring system, and a special circuit to correction, improve the performance of the relevant units laser multidimensional measurement system. The new traceable interferometry method has contributed to the redefinition of mole unit by avogadro constant. It is applied to the high-precision measurement of the diameter of monocrystalline silicon spheres, and the standard uncertainty of measuring the diameter (about 93mm) under laboratory conditions is 5nm. The relevant achievements were rated as “2013 outstanding paper precision measurement award” by international experts, which was the first time that a domestic unit won this award.