On October 29, 1979, BMWi of Germany and the General Administration of Metrology (later AQSIQ and now SAMR) of China signed the Agreement on Measurement Technology Cooperation in Braunschweig, Germany, marking the formal start of China – Germany metrology cooperation (Picture 1-1). Professor Dieter Kind, President of PTB, signed on behalf of Director of BMWi, and China entrusted the specific execution of the Agreement to the NIM located in Beijing and the Branch of NIM (known as the National Institute of Measurement and Testing Technology in 1988) located in Chengdu. Later, this Agreement was renewed every five years, and the Agreement executed now is the Agreement renewed in 2014.
As for the early mode of cooperation, PTB mainly provided technical support for NIM, including training of metrological personnel and provision of the necessary standard instruments. In the 1990s, PTB also trained metrological personnel for provincial metrology institutes, scientific research institutions and universities in China. With the deepening of cooperation, scientific and technological exchanges between the two countries have become more frequent and diverse. Scientific and technological personnel of the two countries have deepened mutual understanding through symposia, seminars, publication of papers via cooperation, etc. The current cooperation between the two countries, especially the cooperation on the study of SI redefinition, is carried out based on technical equality.
In addition to the intergovernmental cooperation agreement signed in 1979, NIM and PTB also signed the Intent on technical cooperation in 2009, which was renewed in 2014. The Intent provided a non-legally binding framework for cooperation between the two institutes, including the description of basic information, such as guest visit projects, technical cooperation contents, etc.
Since the cooperation was started in the 1970s, Professor Zhao Kegong of NIM has played a positive role in the execution of the Agreement. Professor Zhao Kegong is the first PTB visiting scholar from NIM and later served as President of NIM. He developed a new type of laser with very high frequency stability at the Optical Division of PTB, which was one of the standards for the realization of SI definition of the unit meter.
Presidents of PTB, including Professor Kind, Professor Ernst O. Goebel and Professor Joachim Ullrich, were personally responsible for the progress of cooperation.
1. Training of metrological personnel
In the 40-year cooperation, about 400 metrological workers from China were trained by PTB. Most of them came from NIM, and others were from Changcheng Institute of Metrology & Measurement, China Jiliang University, Harbin Institute of Technology, Xi'an University of Science and Technology, Tianjin University and metrology institutes in relevant provinces, such as Xi'an Institute of Measurement and Testing Technology, Zhengzhou Institute of Metrology, Guangzhou Institute of Measurement and Testing Technology, etc. All departments of PTB were involved in the training. The trained personnel included researchers, technicians, testing engineers etc.. Many trained personnel were promoted to leaders in the related fields after their return to China.
In order to overcome language barriers, NIM organized the German training course, about 300 people attended. When NIM developed the 20 MN standard force measuring machine, PTB experts participated in the development of the servo system of the device and applied the development experience of PTB 16.5 MN standard force measuring machine to it. Today, staff of NIM and other metrology institutes are mainly invited to participate in PTB research projects or international cooperation projects.
2. Standard instruments and equipment as gifts
When the cooperation began, PTB developed some standard instruments according to the needs of NIM, such as standard involute gears, high temperature standard tungsten ribbon lamps and their ultraviolet vacuum photometric components. These standard devices played an important role in the development of the Chinese industry. In the 1980s, BMZ provided funds and assisted the Length and Electric Power Labs of NIM in modernization. The Length Lab also received the 2m laser interference comparator from PTB. In the 1990s, BMZ provided assistance for the development of the machine tool industry in China, and helped NIM with the development of metrological scanning tunneling microscope and metrological atomic force microscope and the purchase of high resolution laser interferometer. These two metrological scanning probe microscopes laid a foundation for the development of nanometrology in NIM.
3. Scientific exchanges
As a part of scientific and technological exchanges, both parties organized symposia at all levels, such as the Sino-German Seminar on Micro-Nano Technology and Metrology (funded by DFG and the National Natural Science Foundation of China), Changcheng Institute of Metrology & Measurement - PTB Seminar on Dynamic Measurement and Nanometrology and Legal Metrology Seminar (including the requirements of German water meter manufacturers for export of products to China, and legal metrology under market economy conditions). These symposia will be held alternately between Germany and China. Several Chinese scholars completed their doctoral dissertations during the visit to PTB. For example, Zhao Xianbin, Zhao Yuguang, and Chen Xiaomei, etc. completed their doctoral dissertations at Precision Engineering Division of PTB.
Metrology experts from metrology institutes and universities in China and Germany also published two Chinese textbooks through cooperation in 1997: Coordinate Measuring Machine and Modern Interferometric Measuring Technique.
Based on the measurement cooperation between PTB and NIM, the cooperation between German and Chinese universities was carried out, such as the cooperation between TU Ilmenau and Tianjin University, between RWTH Aachen University and Tsinghua University, etc.
4. Joint research on SI redefinition
NIM finished the time synchronization experiment of its portable cesium atomic clock and PTB atomic clock by satellite in 1979. After that, NIM sent two scholars from the time and frequency lab to PTB for study and work. They proposed the program for the improvement of the cesium atomic clock after they returned to China. After developing the fountain clock, NIM carried out two comparisons with PTB in 2005 and 2009.
NIM took part in the Avogadro constant international cooperation project led by PTB to mainly study how to accurately determine the molar mass of silicon isotope.
The new iodine stabilized He-Ne laser developed by Professor Zhao Kegong was recommended by the General Conference on Weights and Measures as one of the international standards for the realization of meter definition through interferometer.
5. Economic benefits of cooperation
The main economic impacts of China – Germany metrology cooperation are as follows:
◎ Measurement cooperation has unified the test procedures of China and Germany and eliminated trade barriers;
◎ China and Germany realized mutual recognition in the field of Sartorius Banlance and Explosion-Proof ;
◎ Measuring instruments of Sino-German joint ventures can be calibrated by NIM;
◎ NIM has had a positive impact on the sales of German ammeter products in China;
◎ Heidenhhain used the iodine stabilized He-Ne laser developed by Professor Zhao Kegong for the calibration of optical grating. The International Committee of Weights and Measures (CIPM) used this laser as the international standard spectral line for the implementation of SI meter definition;