| 摘要 |
<p>PURPOSE:To improve reliability, to perform a real time measurement, extremely remote monitoring and said measurement by picking up plural lights of refernce wavelength and picking up plural ratios of said light to a light of measuring wavelength. CONSTITUTION:The light emitted at a light source 1 made of light emitting diode and containing at least >=1 among bands of 1.3 and 1.6mum is sent to an optical fiber, e.g., quartz optical fiber 3 of low transmission loss serving as optical transmission path through an optical connector 2. The light is transmitted by the optical fiber to a measuring cell where atmospheric gas is allowed to flow in and out, and absorbed by at least >=1 among 1.666mum and 1.331mum corresponding to characteristic absorption wavelength of gaseous methane at the measuring cell, then sent to a zone transmission filter by the optical fiber of low transmission loss at wavelength band at least >=1 among 1.6mum and 1.3mum. The light is diffracted to a light - measuring wavelength - of absorption wavelength at gaseous methane at least >=1 and the other light of wavelength -reference wavelength - at least >=2, and a ratio of intensity of the light of measuring wavelength to that of the light of reference wavelength is obtained.</p> |
