National Metrology Institute of Japan (NMIJ)

Research Institutes

Fig.1 Seven base units
Fig.1 Seven base units

Research Institutes of NMIJ conduct research and development towards the establishment of primary standards (measurement standards), and dissemination of the measurement standards to societies and industries In cooperation with the Center for Quality Management of Metrology (Metrology Quality Office, Reference Materials Office, Metrology Training Center and Legal Metrology Management Office),.

NMIJ has four research institutes: Research Institute for Engineering Measurement; Research Institute for Physical Measurement; Research Institute for Material and Chemical Measurement; and Research Institute for Measurement and Analytical Instrumentation.

They also carry out technological tasks to link the national measurement standards with those of other countries as well as performing tasks for the government to maintain the accuracy of measuring instruments (specified measuring instruments) necessary for all types of business, taxation, safety and regulations.

Fig.2 Global measurement standards
Fig.2 Global measurement standards

The measurement standards consist of seven base units as shown in Fig.1, and derived units are formed as products of powers of the base units. Research Institutes collaborate with other countries and develop global mechanisms to maintain the equivalence of the measurement standards among domestic and international users. (traceability and mutual recognition arrangement: Fig.2)

Research Institutes Carry Out Tasks Related to Measurement Standards with the Following Goals

  • To provide reliable measurement standards promptly at the social request.
  • To disseminate measurement standards reliably and continuously..
  • To accommodate global standardization of measurement standards under international collaboration.
  • To carry out research and development of measurement standards as leading laboratories

Structure of Research Institutes of NMIJ

         Each research institute houses several research groups.

Research Institute for Engineering Measurement Length Standards Group Research development and supply of length-related standards such as length standards, range finders, deviation amount, etc.
Dimensional Standards Group Research development and supply of dimensional standards centered on coordinate measuring technologies
Nanoscale Standards Group Research development and supply of length standards in nanometer size
Mass Standards Group Reseach development and supply of mass standards, research development of next-generation mass standards
Fluid Property Standards Group Research development of density, viscosity, liquid refractive index and physical properties of fluids
Force and Torque Standards Group Research development and supply of force and torque standards
Pressure and Vacuum Standards Group Research development and supply of pressure and leak standards
Vibration and Hardness Standards Group Research development and supply of vibration and hardness standards
Liquid Flow Standards Group Research development and supply of liquid flow and flow velocity standards
Gas Flow Standards Group Research development and supply of gas flow and flow velocity standards
Type Approval Group Type Approval for specified measuring instruments based on test data and documents
Testing and Inspection Group Inspection of verification standards and Type Approval for specified measuring instruments except for weighing instruments and flow meters
Legal Weighing Metrology Group Conformity assessment tests necessary for inspections of verification standard and Type Approval of mass-related specified measuring instruments
Legal Flow Metrology Group Tests necessary for inspections of verification standard and Type Approval of volume and flow-related specified measuring instruments
Research Institute for Physical Measurement Time Standards Group Research on time standards based on cesium atomic clocks and next-generation time standards by optical lattice clocks
Frequency Measurement Group Research on frequency standards by optical combs/artificial satellites and on frequency measurement/analysis technologies
Quantum Electrical Standards Group Research on precision measurement of direct current voltage, resistance and capacitance based on quantum effects, and industrial application of related standards
Applied Electrical Standards Group Research on precision measurement in alternate current voltage​ and electricity, and industrial applications of related-standards
Radio-Frequency Standards Group Research development of high-frequency electric standards, applied research and international standardization of high-frequency measurement technologies
Electromagnetic Fields Standards Group Development of electromagnetic field and antenna standards technologies, research development of new measurement technologies
Thermometry Research Group Research on thermometry standards, application of standards technologies to industrial thermometry measurements
Applied Radiometry Research Group Research on thermometry standards technologies based on thermal radiation , and non-contact thermometry technologies
Photometry and Radiometry Research Group Research on photometry and radiant quantities and on industrial applications of photometry measurement technologies
Quantum Optical Measurement Group Research on standards in laser radiation flux and single photon, and on industrial applications of laser radiometry
Research Institute for
Material and Chemical Measurement
Inorganic Standards Group Development /maintenance/supply​ of reference materials for analytical equipment, calibration methods and validation, and supply of proficiency tests
Environmental Standards Group Development and sophistication of analysis technologies in environment/food, development of reference materials based on those technologies and supply of proficiency tests
Gas and Humidity Standards Group Development and sophistication of gas analysis and humidity measurement methods, calibration service and development and supply of reference materials
Organic Analytical Standards Group Development and sophistication of organic analysis technologies and supply of reference materials/proficiency tests based on developed technologies
Organic Primary Standards Group Development of evaluation technologies of organic reference materials for equipment calibration and its dissemination, sophistication and rationalization of traceability system
Bio-medical Standards Group Establishment of analysis method to secure credibility in bioanalysis​ and medical diagnosis; development and supply of reference materials
Surface and Nano Analysis Research Group Development and sophistication of surface/nano structure analysis technologies in thin-film/nano materials development, development and supply of reference materials
Nanostructured Materials Characterization Research Group Physical properties evaluation in nanostructured materials necessary for development of functional materials and supply of reference materials for trace elemental analysis
Particle Measurement Research Group Development and supply of reference materials and physical standards in particle measurement, development of advanced measurement technologies, development and standardization of measuring instruments accuracy management technologies
Thermophysical Property Standards Group Development and sophistication of measurement technologies in thermophysical properties, calibration service and supply of reference materials of related quantities
Metrological Information Research Group Development/sophistication/dissemination of measurement information such as database and measurement uncertainty, etc.
Accurate Crystal Structure Analysis Research Group Development and sophistication of precise structure evaluation technologies in nano-level related to development of functional materials and support of designing substance development
Research Institute for Measurement and Analytical Instrumentation Acoustics and Ultrasonics Standards Group Research development and maintenance/supply of acoustics and ultrasonics standards, research development of related precision measurement technologies and related precision measurements​ technologies
Ionizing Radiation Standards Group Development/maintenance/supply of measurement standards in radiation​, research development of related measurement technologies and development of related measurement technologies"
Radioactivity and Neutron Standards Group Development/maintenance/supply of measurement standards in radioactivity and neutron, development of related measurement technologies
X-ray and Positron Measurement Group Research development of measurement technologies using X-ray and positron as probes
Nanoscopic Measurement Group Research development of measurement technologies in nanoregion using electron beam​ and ion beam as probes
Radiation Imaging Measurement Group Research development of visualization measurement technologies using radiation as a probe
Non-destructive Measurement Group Research development of non-destructive measurement technologies with image analysis using ultrasounds
Nanoscale Spectroscopic Measurement Group Research development of spectroscopic measurement technologies in nano region using laser beam

Measurement Standards for Environment, Health and Safety

Reference Materials for Maintaining a Comfortable Environment

Fig.3 Lake sediment certified reference material for analysis of trace elements
Fig.3 Lake sediment certified reference material for analysis of trace elements

Ear thermometers are novel thermometers sensing infrared radiation emitted by the human body. They are being widely used at airport facilities of various countries to test for SARS infection in individuals. The photograph shows the standard blackbody system for the calibration of ear thermometers developed by MD. It is a transportable high-accuracy standard blackbody system that was supplied to overseas institutes such as those in Singapore, and its use contributed effectively to prevention of a SARS epidemic in Asian countries.

Gamma-ray Standards Contributing to Human Safety

Fig.4 Cylindrical graphite cavity ionization chambers (right: approx. Φ50 x 70 mm)
Fig.4 Cylindrical graphite cavity ionization chambers (right: approx. Φ50 x 70 mm)

Radio waves used in cell phones and wireless LANs became essential in daily life. It is necessary to utilize a space in which the minimum possible scattering and reflection of waves from the surroundings are ensured to enable accurate measurement of the strengths of electric and magnetic fields and standard antennas. An open-area test site is used as an outdoor measurement field for the frequencies from 30 MHz to 1 GHz. An electromagnetic anechoic chamber (24 m x 15 m x 9 m) with surrounding walls, a ceiling and a floor constructed as close to nonreflecting as possible, is used as an indoor measurement field for frequencies of up to 40 GHz.

Calibration Facility for Infrared Ear Thermometers Contributing to Prevention of a SARS Epidemic

Fig.5 Standard blackbody for ear thermometers
Fig.5 Standard blackbody for ear thermometers

The spectral database compiles information on six standard spectra (infrared, nuclear magnetic resonance (two types), mass, electron spin resonance and Raman spectra) of approximately 30,300 chemical compounds. These spectra have been collected since the 1980s and the data have been made available on the internet freely since 1997. They are frequently accessed globally.

Measurement Facility for Electromagnetic Fields and Antenna Standards

Fig.6a The north site electromagnetic wave measurement facility ( open-area test site for outdoor measurement )
Fig.6a The north site electromagnetic wave measurement facility ( open-area test site for outdoor measurement )
Fig.6b The north site electromagnetic wave measurement facility ( electromagnetic anechoic chamber for indoor measurement )
Fig.6b The north site electromagnetic wave measurement facility ( electromagnetic anechoic chamber for indoor measurement )

The importance of flatness measurement is increasing in many fields, for example measurement of silicon wafers for semiconductors, hard disk substrates, glass for liquid crystal display, and so on. The instrument developed at MIJ measures flatness by comparing a specimen with a precisely polished reference optical flat using Fizeau interferometry.It has a 310-mm-diameter measurement area which covers a 12-inch silicon wafer.

Spectral Database Essential for Chemical Analyses

Fig.7 Spectral database
Fig.7 Spectral database

Gamma-ray and X-ray are used in the vicinity of nuclear facilities, and for medical diagnosis and therapy; it is important to measure these rays accurately to ensure human safety and health. National standards for gamma-ray are established using the graphite cavity ionization chamber shown in the photograph. The values of personal monitors used in the vicinity of facilities utilizing ionizing radiation are calibrated on the basis of the reference standards of MIJ.

Measurement Standard Technology Contributing to Industries

Flatness Measurements Essential to the Semiconductor Industry

Fig.8 Large-aperture flatness interferometer
Fig.8 Large-aperture flatness interferometer

High-accuracy angle measurements are required in places such as the arm joints of robots and the rotation mechanism of paper feeders of printers; rotary encoders are used in many of these places. To calibrate high-accuracy rotary encoders, MIJ succeeded in developing a rotary encoder angle self-calibration system with the world's highest accuracy, enabling calibration at an accuracy of approximately 0.01" using the equal division averaged method (Masuda-Kajitani method).
(Collaborative research with Shizuoka Institute of Science and Technology and University of Electro-Communications)

High-accuracy Angle Standard for Use in Robots

Fig.9 Rotary encoder calibration system
Fig.9 Rotary encoder calibration system

High-accuracy angle measurements are required in places such as the arm joints of robots and the rotation mechanism of paper feeders of printers; rotary encoders are used in many of these places. To calibrate high-accuracy rotary encoders, MIJ succeeded in developing a rotary encoder angle self-calibration system with the world's highest accuracy, enabling calibration at an accuracy of approximately 0.01" using the equal division averaged method (Masuda-Kajitani method).
(Collaborative research with Shizuoka Institute of Science and Technology and University of Electro-Communications)

Measurement of Thin-Film Thermophysical Properties and Reference Thin-Film

Fig.10 Ultra-fast temperature responses of molybdenum thin films
Fig.10 Ultra-fast temperature responses of molybdenum thin films

A pico-second thermoreflectance measurement system has been developed in order to measure thermal diffusivities of thin films thinner than 1 micrometer. A film face of a transparent substrate side is heated by a pico-second laser pulse. Heat generated by the pump laser pulse diffuses towards the front surface of the thin film. The temperature change on the front surface opposite to the heated area is measured by the reflected intensity of probe pico-second laser pulse. The heat diffusion across molybdenum thin films with thickness of 75, 120, and 200 nm has been observed successfully for the first time in the world. Based on this technique, MIJ are now developing the thin film thermal diffusivity standard and reference thin films for thermal diffusivity measurements.

Common Measures for Chemical Analysis

Fig.11 Purity determination methods and SI traceability
Fig.11 Purity determination methods and SI traceability

For chemical analysis, traceability to the international system of units (SI) has become important. As methods considered to be potentially the primary methods of measurement in realizing traceability to SI, titrimetry, gravimetric analysis and coulometric titration play major roles, particularly in the field of inorganic analysis. For example, it is possible to directly compare moles by applying EDTA chelatometric titration to many inorganic standard solutions. Gravimetric analysis is ultimately traceable to Prototype Kilogram. Coulometric titration is based on Faraday's law; it is used to realize a mole using current and time without any reference material.

New Measurement Standards

Atomic Clock with an Error of 1 Sec Per 20 Million Years

Fig.12 Atomic fountain primary time and frequency standard
Fig.12 Atomic fountain primary time and frequency standard

The thermal motion of atoms was the most significant factor limiting the accuracy of time standard. MIJ has developed a high-accuracy atomic clock the error of which is only 1 sec per 20 million years by freezing the motion of atoms using pressure generated by a laser beam. The high-accuracy atomic clock is used to monitor and calibrate the coordinated universal time, which is the foundation of today's time system.

Proposal for a New Mass Standard Replacing the Prototype of the Kilogram

Fig.13 Optical interferometer to determine diameters of the silicon spheres
Fig.13 Optical interferometer to determine diameters of the silicon spheres

The kilogram is the only SI base unit still defined by an artifact, the prototype of the kilogram. For replacing the present definition of the unit to an atomic mass standard that is traceable to the mass of a single 12C atom, the Avogadro constant is being determined at MIJ by the X-ray crystal density method. This method determines the Avogadro constant by absolute measurements of the lattice constant using an x-ray interferometer, density using an optical interferometer and molar mass using a mass spectrometer for an identical silicon crystal. To realize the new definition, the Avogadro constant must be determined with a reduced uncertainty. For this purpose, technologies that measure the lattice constant, density and molar mass more accurately are being developed.

New Temperature Scale for Ultra-high Temperatures Exceeding 1000 °C

Fig.14 Calibration of radiation thermometer using a high-temperature standard of metal and carbon alloy
Fig.14 Calibration of radiation thermometer using a high-temperature standard of metal and carbon alloy

A temperature scale exceeding 1000 °C is essential in the technological development in various fields such as space and aeronautical materials, nuclear materials, and nuclear fusion. Conventionally, temperature fixed points for realizing temperature scale has been defined up to approximately 1100 °C. MIJ is the first to realize fixed points of alloys of metal and carbon as temperature standards for temperature regions exceeding 3000 °C.

In the photograph below, on the left, light is radiating from a black body into which a eutectic alloy of iridium and carbon is cast at its melting point, approximately 2300 °C. On the right, a radiation thermometer is calibrated based on the intensity of the radiation.

Worlds First Liquid-Helium-Free Voltage Standard

Fig.15 Liquid-helium-free programmable Josephson device
Fig.15 Liquid-helium-free programmable Josephson device

MIJ is developing a "liquid helium-free programmable Josephson voltage standard" using an NbN/TiN/NbN device that is operable at approximately 10 K using a small freezer as the next generation voltage standard. If this system is introduced, not only will liquid helium, which is essential in conventional systems, become unnecessary, but a substantial reduction in the price of the system and in the maintenance cost will be realized. In the near future, high-accuracy voltage standards can be generated solely based on the availability of a 100 V AC power source.