| Project/Area Number |
09650453
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
計測・制御工学
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| Research Institution | Yamagata |
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Principal Investigator |
HIRANAKA Yukio Yamagata University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40134465)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | visualization / sound field / TOF / atmospheric particles / optical sing-around / 光距離計測 / 音場可視化 / パルスレーザ / 光ループ発振 / 浮遊塵 |
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| Research Abstract |
Optical remote sensing is a most desired way to visualize acoustic fields, because otherwise they would be easily disturbed by a physical sensor itself. Our method is to detect vibrations of floating dust particles in air by time-of-flight measurements such as used in lidars. It is required to measure m sub femto-second to pico-second resolution so that we can detect vibrations ranging from one hundredth micrometer to one milimeter for 100Hz audible sound. To perform such high precision measurements, we propose to use a sing-around oscillation of light pulses. The measuring system includes a 10MHz repetition 5Ops pulse laser, a photo-multiplier-tube as the detector, a pulse counter and a time interval analyzer. Standard deviation for single transits was 70ps for a fixed flight length. By averaging them, standard deviation of resulting mean values may be reduced by the factor of square root of averaging samples. Sing-around accumulation and division will give us linear reduction by the number of averaging samples. One crucial thing .to optical sing-around is to get enough reflection from a target. A PLL like compensation circuitry for loss-of-reflection is proposed and analyzed for preventing oscillation stopping. Future works are needed for acquiring practical resolution with a powerful laser source, scanning spatial, and detecting three dimensional vibrations.
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