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Research paper−246−Synthesiology - English edition Vol.2 No.4 pp.246-257 (Feb. 2010) reached, the latest, most advanced, and special technologies become barriers in supplying and maintaining the standard due to high cost and difficult availability, which are factors that cannot be neglected.When the author started research on precision interferometry at the former National Research Laboratory for Metrology, Agency of Industrial Science and Technology (current National Metrology Institute of Japan, AIST), the iodine-stabilized He-Ne laser used as wavelength standard (this was national standard of length in Japan to 2009) faced such problems. In the beginning, although I experienced poor operability and problems in procuring the special parts, I thought they were unavoidable hardships for the upkeep of a national standard with highest precision. At that time, a researcher of Physics and Engineering Laboratory of New Zealand (the National Standards Laboratory) was visiting the standard labs of various countries and stopped at AIST to conduct an international comparison of iodine stabilized He-Ne lasers[1]. He hand-carried a self-developed laser onto the passenger cabin of the airplane. Compared to the Japanese laser that was composed of a rack full of control components and the laser body installed on a cast-iron channel bench, I was absolutely amazed by its compact size and easy operability.Inspired by this experience, I started research on the universalization of the iodine stabilized He-Ne laser. Here, “universalization” means to carefully study and to clarify the functions and properties required for each member of the iodine stabilized He-Ne laser, and then to achieve these functions and properties using generally available parts as much as possible. In this paper, I shall describe the 1 IntroductionThe length is one of the most basic physical quantities, and the technology for measuring the length is highly advanced in the fields of science and industry. The international unit for length is the meter (or metre). The International Prototype of "X" cross-section metre line-standard was used as the standard since the latter half of the 19th Century, and in the 20th Century, a definition of the metre in terms of the wavelength in vacuum of the radiation corresponding to a transition between specified energy levels of the krypton 86 atom was adopted in 1960. The current definition of the metre has been adopted since 1983, and this is based on the speed of light traveling in vacuum (light velocity)Note 1). Specifically, the standard is the wavelength of laser radiation under specific conditions. The most widely used standard is the helium-neon laser with its laser wavelength stabilized to the absorption line of iodine moleculesNote 2). Currently many countries around the world including Japan use the iodine-stabilized He-Ne laser as their national standards. Figure 1 is the traceability system of length measurement using this laser as the national standard.In general, the national standard is expected to possess the highest precision above the measurement precision required in industry and academia. Therefore, the latest, most advanced, and special technologies are summoned to achieve the highest precision in the development of the national standard. When the R&D is completed and the national standard is created, the next phase is how the standard is supplied effectively to industry and academia, and how to maintain this national standard stably. Once this supply phase is - An advanced mechanical design for the iodine stabilized He-Ne laser -Jun IshikawaDigital Manufacturing Research Center, AIST Tsukuba East, 1-2-1 Namiki, Tsukuba 305-8564, Japan E-mail : Original manuscript received May 22, 2009, Revisions received September 24, 2009, Accepted September 25, 2009The iodine stabilized He-Ne laser at 633 nm is widely used as the national length (wavelength) standards in many countries. Since the wavelength emitted by the laser is directly proportional to the cavity length of the laser, extremely high mechanical stability is necessary for the cavity of the iodine stabilized He-Ne laser. Many special parts as well as special materials are adopted to achieve a sufficiently high stability in the conventional iodine stabilized He-Ne lasers while the adoption of such special parts and materials brings difficulty in the maintenance of the lasers. I developed and constructed a new iodine stabilized He-Ne laser with a special mechanical design. The assembly and adjustment of the laser is quite easy. Although most parts and materials of the laser are commercially available, it showed better stability especially against the ambient temperature variation. The new iodine stabilized He-Ne lasers were used for a long time as the national length standards of Japan.Portable national length standards designed and constructed using commercially available partsKeywords : Mechanical design, fine mechanism, anti-vibration mechanism, length standard, iodine stabilized He-Ne laser[Translation from Synthesiology, Vol.2, No.4, p.276-287 (2009)]

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