Vol.2 No.4 2010

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Research paper : Portable national length standards designed and constructed using commercially available parts (J. Ishikawa)−257−Synthesiology - English edition Vol.2 No.4 (2010) 6 What happened to the overseas researcherQuestion (Akira Ono)The researcher from New Zealand inspired you to carry out your idea. What kind of research did this researcher do afterwards? Can you answer to the extent you know?Answer (Jun Ishikawa)After that, due to the administrative reform in New Zealand, many research institutes were reduced, abolished, or merged, and I’ve heard from his successor that the researcher transferred to a private company. New Zealand’s iodine stabilized He-Ne laser is currently an American product, and it’s a little sad to hear that the laser that he used for the international comparison is no longer used and sits in the corner of the lab.7 Examples of Product Realization Research conducted by overseas national standards laboratoryQuestion and comment (Akira Ono)The universalization research for the national standard that you conducted can be considered a Product Realization Research. I don’t think there are so many examples in the AIST Metrology Standard Groups engaging in research with a clear goal of product realization. However, some researches such as “remote calibration” are being done in the mid-tier of the traceability system involving the calibration service providers, and it seems that you are strongly aware of the importance of Product Realization Research.Around the world, to the best of the author’s knowledge, is there any example, other than New Zealand, of such Product Realization Research done by a national standard laboratory?Answer (Jun Ishikawa)Attempts at product realization of iodine stabilized He-Ne laser was done from its early stages (around 1980), but it mostly involved the manufacturers almost entirely copying the R&D product from the laboratory to create the product. As a result, there were problems in price, size, and operability, and it was not of high quality as a product. The laser from New Zealand was developed from the user’s standpoint for the purpose of using it for international comparison. It had outstanding portability and operability at that time. Although the laser never became a product in New Zealand, I think it is essential to carry out the universalization research from the user’s standpoint to achieve successful product realization. I don’t know so many examples where universalization research was carried out from the user’s standpoint for a device with highly specialized purpose such as the iodine stabilized He-Ne laser. However, product realizations for more general devices (such as the mirror holder) have been done at national standards laboratories, and these have superior performances compared to the conventional products from manufacturers.the resonator is too large. However, I think this includes the gas lens effect and gas prism effect that were difficult to assess separately in the conventional iodine stabilized He-Ne laser that had problems with linearity in its control mechanism. The researcher who has been working on iodine stabilized He-Ne laser for a long time at the Bureau International des Poids et Mesures acknowledged this point.Since the linearity of the control mechanism of the new laser is excellent, the gas lens and gas prism effects can be separated, and the uncertainty budget will be as shown in Table “b”. To reduce the uncertainty due to gas lens and gas prism effects, it is necessary to precisely fabricate the geometric shape of the laser discharge tube, and such laser tube is not available in reality. The effect of purity of iodine was reduced by improving the filling process of the iodine cell, and the uncertainty of beat frequency measurement was reduced by improving the measurement technology.5 Precision of the standard owned by the calibration service providerQuestion (Akira Ono)You say that several calibration service providers in Japan own the iodine stabilized He-Ne laser as their own standards, and I believe they are brought to AIST for regular calibration. When the calibration was conducted, what was the difference compared to the wavelength (frequency) of the national standard at AIST. Did it fall within the range of uncertainty assessed for the new laser, or did some of them surpass the range?Answer (Jun Ishikawa)The new lasers were all assembled and adjusted under the author’s technological instruction at AIST. Therefore, the frequency difference of 5 kHz or less against the national standard was checked at the time of shipment. Except for the case where the emission ceased due to clouding of the optical window, I confirmed that the initial performance was almost completely maintained at the time of recalibration.Table a Uncertainty of the iodine stabilized He-Ne laser recommended by the CIPM.Table b Uncertainty of the new iodine stabilized He-Ne laser.Combined standard uncertainty10.05.0Uncertainty of beat frequency measurement5.0<1.0 kHz/mW10 mWOne-way intracavity beam power-10 kHz/MHzFrequency modulation width peak-to-peak 3.05.0Effect of iodine purity3.0-15 kHz/℃0.2℃15 ℃Cold-finger temperature2.50.5 kHz/℃5 ℃25 ℃Wall temperatureIodine cellUncertainty(kHz)CoefficientRecommended valueParameterTolerance6 MHz0.3 MHz5 mW6.35.00.02.0<1.0 kHz/mW10 mW-10 kHz/MHz2.02.01.5-15 kHz/℃0.1℃15 ℃1.00.5 kHz/℃2 ℃23 ℃6 MHz0.2 MHz2 mWCombined standard uncertaintyUncertainty of beat frequency measurementOne-way intracavity beam powerFrequency modulation width peak-to-peak Effect of iodine purityCold-finger temperatureWall temperatureIodine cellUncertainty(kHz)CoefficientRecommended valueParameterToleranceGas lens effect, gas prism effect

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