NMIJ plays a significant global role in the time and length field, ranging from time standards of the world lowest uncertainty to practical length standards supported by standards technology unique to Japan. We have vigorously engaged in development of such standards, and numerous achievements are now being delivered. Taking both these domestic circumstances and the international circumstances under the Meter Convention into consideration, we contribute to the establishment and dissemination of new standards. Furthermore, we continue to conduct research and development activities and other related operations in order to establish standards not only for next-generation but also currently in demand.    

The Coordinated Universal Time (UTC) is the world standard for time and is appropriately calibrated by a few primary frequency standards developed in major advanced countries. The optically pumped cesium frequency standard developed by NMIJ has an uncertainty of 2.9 × 10^-14 and, as one of the primary frequency standards, has already contributed to the establishment of UTC. We are currently involved in developing a "cesium atomic fountain frequency standard" to further improve the precision of the frequency standard. In this cesium standard, cesium atoms are trapped with by the radiation pressure of laser light, launched upward, like a fountain, and fallen by the gravity. It is expected that uncertainty is improved by more than a factor of ten.     [ Time Standards Section ]

We have developed an acetylene stabilized semiconductor laser, a reference standard for an optical frequency (wavelength) of around 1.5 µm, an important wavelength for the optical communication band, by stabilizing the frequency of a semiconductor laser at the center of the saturated absorption frequency of acetylene molecules. This new laser was approved by the Meter Convention's Consultative Committee for Length, held in the fall of 2001, for inclusion in the list of lasers that define the meter. This laser is the first laser for the optical communication band in the list. With the acetylene stabilized semiconductor laser, we are now capable of providing standards that can satisfy a sufficient level of uncertainty (9 to 10 orders of magnitude) for applications unable to be fully covered by commercially available wavelength meters with an uncertainty of 6 orders of magnitude. This research was jointly conducted with the University of Electro-Communications and Tokyo Institute of Technology.     [ Wavelength Standards Section ]

The portable iodine-stabilized Nd: a YAG laser system has major potential to provide a new wavelength and an optical frequency standard, and is currently being studied in a number of countries. Frequency control is conducted based on the hyperfine structure of iodine molecules, with the level of uncertainty so far achieved being 10^-12 (one trillionth).     [ Wavelength Standards Section ]

NMIJ is engaged in research into a high precision calibration system for optical frequency (wavelength) for a wide range of wavelengths (500 nm to 1100 nm) by using a femtosecond mode-locked laser. This system is designed to calibrate optical-band frequencies (hundreds of THz) of frequency stabilized lasers by cesium frequency standards (9 GHz), and to integrate frequency standards with wavelength standards. We also study how to improve the efficiency of calibration services by developing remote frequency calibration technology that utilizes GPS satellites or the Internet.     [ Time and Frequency Division ]

Precision measurements based on the length standard are very important, and their significance is growing with the advancement of science and industrial technology. Particularly important is product quality improvement in production processes, and international comparison that demonstrate multinational equivalence in standards. To meet these demands, NMIJ focus on research and development of advanced technology for measurement of length and geometrical quantities to provide accurate standards, and engage in frequent implementation of international comparisons, improvement of technical manuals and handbooks, and supply of quality standards.    

In addition to the quantities for which standards are already supplied (gauge blocks, long gauge blocks, line standards, and distance meters), NMIJ is developing standards of internationally and domestically important quantities (interferometric instruments and digital scales). Wider diffusion of length standards through development of high-resolution length measuring technology is also one of our key tasks.     [ Length Standards Section ]

Our research activities in the field of dimensional standards include the establishment of geometrical standards (straightness, flatness, roundness, and three-dimensional coordinates measurements), critical dimension and micro shape standards (one-dimensional and two-dimensional gratings, step height, and surface roughness), angle standards (rotary encoders, polygons, and autocollimators), provision of standards, international comparisons, and state-of-the-art measuring technologies, such as nanometrology. In such research are used probe technologies, using laser light, probes, and electron beams, and various interferometers using laser light sources traceable to the wavelength standard.     [ Dimensional Standards Section ]

NMIJ is engaged in research into automatic correction of air refractivity, remote length measuring technology using the Internet or optical fiber lines, measurement technology for applications of femtosecond pulse lasers, measurement technology for low-coherence interference applications, laser tracking. X-ray application technology to establish calibration technology of greater precision and efficiency. NMIJ is one of the core organizations in the international standards research community.     [ Dimensional Standards Section ]