| 摘要 |
Apparatus for measuring the absorption of a gaseous sample and particularly suitable for measuring the concentration of gaseous oxygen makes use of a diode laser (16) whose emission wavelength is adjacent to but spaced from the wavelength of a distinct absorption line. The diode drive current is altered to cause the junction temperature of the laser to change, thereby changing the wavelength of the emitted radiation and in effect scanning it through a range of wavelengths that includes the absorption line. The absorption is determined by a ratio technique and therefore is independent of changes in the laser output power level and drifts and changes in other parts of the optical system. |
