| Project/Area Number |
17360062
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Production engineering/Processing studies
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
AKETAGAWA Masato Nagaoka University of Technology, Mechanical Department, Associate Prof. (10231854)
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| Co-Investigator(Kenkyū-buntansha) |
YANAGI Kazuhisa Nagaoka University of Technology, Mechanical Department, Prof (80108216)
NAMERIKAWA Toru Kanazawa University, Graduate School of Natural Science and Technology, 准教授 (30262554)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥15,810,000 (Direct Cost: ¥15,600,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2005: ¥10,300,000 (Direct Cost: ¥10,300,000)
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| Keywords | meter definition / picometer / interferometer / phase modulation / lock-in detection / null method / frequency / external cavity laser diode / 超精密計測 / ナノメートル / トレーサビリティ / 光周波数 / ナノメトロロジー / ビート周波数 |
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| Research Abstract |
Meter definition shows the length can be determined from frequency through the speed of light. From the theory, we have developed a displacement measuring interferometer with picometer resolution from frequency shift.
We have developed a phase modulation homodyne interferometer using an electricaloptical-modulator (EOM) and external cavity laser diode (ECLD). In the PMHI, a phase of an incident light from the ECLD is modulated with an EOM and the output signal of a photodiode at the end of interferometer is demodulated with the modulation signal using a lock-in amplifier. From this configuration, it is possible to determine an optical path difference L of wavelength A integer N(mode number) with accuracy of 10 pm or less using the null-method, because the lock-in demodulation can transfer a dark fringe(in the case, L=λN) into a null-cross-point of the lock-in output signal. In the proposed instrument, a displacement of movable mirror can be converted to a frequency shift of the ECLD. The frequency shift of the ECLD is determined from a beat signal between the ECLD and a frequency stabilized He-Ne laser. Using the aid, following results are obtained.
(1) We have examined non-linear interpolation error of a commercial heterodyne interferometer using the proposed method. We clarified that the interpolation error has periodical error corresponding to the wavelength of the light source in the heterodyne interferometer.
(2) We have directly measured a free spectral range (FSR) for a optical path difference of the PMHI using two ECLDs, which are locked at adjacent null-cross-points.
(3) We have measured an air-refractive-index fluctuation from the frequency shift of the ECLD. In the case, the PMHI is made of ultra-low-thermal expansion ceramics. The measured air-refractive-index fluctuation is well coincided with the theoretical one with Ciddor's equation using a temperature, humidity, CO2 contents and air-pressure.
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