Baseline correction for stray light in log-ratio diode laser absorption measurements

Abstract

Log-ratio detection is a convenient technique for making temperature and concentration measurements using sensors based on tunable diode laser absorption spectroscopy. In many practical sensing applications, it is difficult to avoid stray light falling on the signal photodiode of the sensor. This stray light acts as noncommon-mode interference and introduces a systematic error in absorption measurements, which is not removed by baseline subtraction. This paper analyzes the factors that determine this systematic error and also presents a calibration method that can correct for it. This correction method is verified using a simple experiment.

Gas sensing technologies in combustion: A comprehensive review

“…Figure 16. Oxygen absorption A-band [28] The detection wavelengths and limits of some combustion gases are summarized in Table 1.…”

Rugged, Scramjet Inlet Temperature and Velocity Sensor: Design and Ground Test

“…This largely mitigated the effects of thermal drift but maintained the sensitivity of the dual-beam approach. The ac coupling (and any baseline drift due to stray light) must be accounted for in the analysis of the data [6,22].…”