| Project/Area Number |
01850091
|
|---|
| Research Category |
Grant-in-Aid for Developmental Scientific Research
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
計測・制御工学
|
|---|
| Research Institution | Okayama University. |
|---|
Principal Investigator |
KOGA Ryuji Okayama Univ., Fac. Engineering, Professor., 工学部, 教授 (20027147)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
WADA Osami Okayama Univ., Fac. Eng., Lecturer., 工学部, 講師 (10210973)
SANO Hiroya Fukuyama Univ., Fac. Eng., Professor., 工学部, 教授 (10033143)
KOSAKA Megumi Okayama Univ., Fac. Eng., Teaching Assistant., 工学部, 教務員 (00170233)
|
|---|
| Project Period (FY) |
1989 – 1991
|
| Project Status |
Completed (Fiscal Year 1991)
|
| Budget Amount *help |
¥12,500,000 (Direct Cost: ¥12,500,000)
Fiscal Year 1991: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1990: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1989: ¥10,100,000 (Direct Cost: ¥10,100,000)
|
|---|
| Keywords | Atmosphere / Methane / Concentration / Real-Time / Non-contact / Long-path / Scintillation / Tunable-Diode-Laser / 鉛塩半導体レ-ザ |
|---|
| Research Abstract |
A device to measure atmospheric methane concentration has been developed. Its principle is based on measuring the absorption spectrum of atmosphere along the laser beam running over a long-path of 1 to 150m through open air. A PbSnTe tunable diode laser-fabricated by Fujitsu Laboratories Ltd. was employed, which covers the nu_4 band around nu=1300 cm^<-1> at around 77K of the diode temperature. Theoretical sensitivity is as low as 0.8 ppb with 50m optical path length.
A portable device was constructed comprising an optical head, a retro-reflector, an electronic systems and a personal computer along with a battery power supply. Temporal resolution is possible to be as short as 10 seconds for each measured concentration of methane.
Subjects to be newly developed were the optical architecturecomprising laser-beam transmitter/ receiver and corner-cube retroreflectors, electronic circuit system's to extract the second higher harmonic spectrum and the software that derive methane concentration from the measured spectrum suppressing spectral interferences.
Three measurements which are continuous for 24 or 48 hours were achieved in the experimental rice-paddy field of Okayama University. A quick response of atmospheric methane density to soil temperature were confirmed. This is due to the non-contact and real-tithe characteristic of our device in contrast to the chamber method. Results are compared with those by the gas chromatography and by, -the chamber method. The device was safe after two sudden rain-storms attacked it, which eventually demonstrated the reliability of the device.
Additional research on the atmospheric scintillation in the far infrared region were carried for the further improvement of this system.
|
