1.
Introduction
The Electrotechnical Laboratory (ETL) is one of the largest national
research institutes in Japan, and is affiliated with Agency of Industrial
Science and Technology (AIST) and the Ministry of International
Trade and Industry (MITI). ETL enjoys the great advantage of a general
research laboratory for conducting comprehensive and intersectional
research in various fields. In particular, ETL is responsible for
the standards for electricity (DC, LF, and RF), sound, photometry
and radiometry, ionizing radiation, and vacuums. It oversees services
for calibrating various gauges with these standards under a traceability
program, type certification, and inspection of standard gauges based
on the Measurement Law.
2.
Research Activities for Standards at ETL
2.1 DC and LF Electrical Standards
The DC voltage standard, realized using the Josephson effect, is
known officially as the Specific Standard of DC Voltage under the
Measurement Law. ETL provides calibration service under this law
(seven cases in fiscal 1996), and has conducted international DC
voltage comparisons. Other work has included characterizing Zener
voltage references, studying Josephson array production for voltage
standards, and developing a divider to calibrate 1 kV. The DC resistance
standard, realized using the quantum Hall effect, is known officially
as the Specific Standard of DC Resistance. ETL provides calibration
service under this law (eight cases in fiscal 1996), and has conducted
international DC resistance comparisons. Other work has included
characterizing standard resistors and developing high-resistance
calibration technology. A new capacitance standard based on the
quantum Hall effect resistance standard has been developed, and
a precise ratio transformer fabricated and evaluated. A study was
also conducted to evaluate the possibility of realizing a quantum
current standard using single electron tunneling phenomena in small
junctions is investigated.
ETL is focusing on new microwave, millimeter-wave, and laser radiation
measurement techniques and the development of new electromagnetic
standards such as RF attenuation, microwave impedance, coaxial noise,
electromagnetic fields, RF power, and laser power standards. The
quantum mechanical state control of electromagnetic radiation is
being applied to precise electromagnetic wave measurements and to
applications in the microwave region, and precise physical standards
are being set up.
2.2 Acoustic Standards
ETL has improved the calibration accuracy of standard condenser
microphones with an acoustic coupler, has developed free-field calibration
for microphones using an anechoic chamber,
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Naoto Kobayashi
Director,Quantum
Radiation Division
and Chairman of the
Standards
Promotion Committe |
and has designed control techniques for sound fields in ordinary
rooms for the sound pressure level standard in the audible frequency
range. Auditory sense measuring techniques, which are important
for evaluating environmental noise, have also been studied.
2.3 Radiation, Radioactivity, and Photometric Standards
Precise measurements relevant to radiation, radioactivity, and
photometric standards such as absorbed dose, air kerma activity,
neutron fluence, luminous intensity, luminous flux, spectral responsivity,
and spectral irradiance have been conducted. For this purpose, ETL
is exploring new types of radiation for this research, such as high-energy
electron beams and X-rays, high-intensity positrons generated by
a 500-MeV electron linear accelerator, synchrotron radiation (SR)
generated by an 800-MeV electron storage ring and compact storage
rings and high-intensity neutrons generated by a 0.3-MV and a 4
MeV ion accelerator.
2.4 Vacuum (low pressure) Standards
In order to calibrate a vacuum gauge for low-pressure measurements,
a standard pressure field of a known value is first created, and
then the gauge is calibrated against the standard pressure. A standard
pressure value can be produced by the expansion method, in which
a high-pressure gas is expanded in a vacuum chamber to a specific
volume on the basis of Boyle's law, and by the orifice flow method,
which uses a molecular gas flow. The former method is suitable for
generating a pressure of approximately 10-4Pa or higher, and the
latter for a pressure of 10-2Pa or lower.
3. ETL as a Member of APMP
ETL has long been engaged in R&D and calibration services in
the measurement standards in Japan, and it is a great pleasure to
take part in the APMP. Since the global Mutual Recognition Arrangement
(MRA) of national measurement standards and of calibration and measurement
certificates became effective in October 1999, the role of the APMP
has been of great importance. ETL is prepared to be a responsible
member of the APMP, based on its long and extended research activities
in standards and measurements.
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