文档介绍：Diode-laser absorption sensor for line-of-sight
gas temperature distributions
Scott T. Sanders, Jian Wang, Jay B. Jeffries, and Ronald K. Hanson
Line-of-sight diode-laser absorption techniques have been extended to enable temperature measure-
ments in nonuniform-property flows. The sensing strategy for such flows exploits the broad wavelength-
scanning abilities nm Ϸ 30 cmϪ1͒ of a vertical cavity surface-emitting laser ͑VCSEL͒ to interrogate
multiple absorption transitions along a single line of sight. To demonstrate the strategy, a VCSEL-
based sensor for oxygen gas temperature distributions was developed. A VCSEL beam was directed
through paths containing atmospheric-pressure air with known ͑and relatively simple͒ temperature
distributions in the 200–700 K range. The VCSEL was scanned over ten transitions in the R branch of
the oxygen A band near 760 nm and optionally over six transitions in the P branch. Temperature
distribution information can be inferred from these scans because the line strength of each probed
transition has a unique temperature dependence; the measurement accuracy and resolution depend on
the details of this temperature dependence and on the total number of lines scanned. The performance
of the sensing strategy can be optimized and predicted theoretically. Because the sensor exhibits a fast
time response ͑ϳ30 ms͒ and can be adapted to probe a variety of species over a range of temperatures and
pressures, it shows promise for industrial application. © 2001 Optical Society of America
OCIS codes: , , , , , .
1. Introduction flows. The sensing strategy is enabled by recently
Nontomographic line-of-sight absorption sensors for developed vertical cavity surface-emitting laser
gas temperature and species concentration tradition- ͑VCSEL͒ sources that provide rapid single-mode
ally have been limited to flows with near-uniform scans over a broad wavelength range