초록 ▼

A system and method for determining the concentration of an analyte such as oxygen in an unknown gas sample. A Vertical Cavity Surface Emitting Laser (VCSEL) is used as a variable wavelength light source which is "swept" through a wavelength range by varying the drive signal applied thereto. Quantit

A system and method for determining the concentration of an analyte such as oxygen in an unknown gas sample. A Vertical Cavity Surface Emitting Laser (VCSEL) is used as a variable wavelength light source which is "swept" through a wavelength range by varying the drive signal applied thereto. Quantitative spectroscopic analysis of the unknown gas sample is performed without the requirement of feedback circuitry for tuning the light source to the characteristic frequency of an analyte. Instead, the VCSEL is repeatedly "swept" through a range of frequencies determined by the drive signal, and the absorption is measured by the detector. The absorption lines do not always occur at the same place but instead move along around during the sweep based on the temperature and baseline current. The absorption at a particular wavelength may be determined by overlaying the drive signal and its timing information over the detected absorption signal.

대표청구항 ▼

[ We claim:] [1.] A gas analyzer for detecting the concentration of a gaseous component of a gas sample, comprising:a sample cell containing an unknown concentration of said gaseous component;a driving circuit which generates a laser driving signal;a laser light source which outputs laser light that

[ We claim:] [1.] A gas analyzer for detecting the concentration of a gaseous component of a gas sample, comprising:a sample cell containing an unknown concentration of said gaseous component;a driving circuit which generates a laser driving signal;a laser light source which outputs laser light that is continuously varied through a range of frequencies including a characteristic absorption frequency of said gaseous component in response to said laser driving signal and that is not locked or tuned to said characteristic absorption frequency of said gaseous component, said continuously varying laser light being directed through said sample cell whereby laser light at said characteristic absorption frequency may be absorbed in proportion to the concentration of said gaseous component in said sample cell;a detector which detects laser light in said range of frequencies which has passed through said sample cell and which has been absorbed at the characteristic absorption frequency of said gaseous component to provide a detection output; anda compensation circuit which demodulates said detection output to remove said laser driving signal so as to leave an absorption signal with characteristic absorption lines at points in said absorption signal where said laser light source outputs light at said characteristic absorption frequency of said gaseous component, a magnitude of said characteristic absorption lines being proportional to the concentration of said gaseous component in said gas sample.