Endress+Hauser SpectraSensors SS500 - Figure 1-2 Typical Raw Signal from a Tunable Diode Laser Absorption Spectrometer with and Without Mirror Contamination; Figure 1-3 Typical Normalized Absorption Signal from a Tunable Diode Laser Absorption Spectrometer

SS500/SS2000 Analyzer
1–6 4900002285 rev. B 3-25-20
of raw data results from ramping the current to tune the laser, which not only
increases the wavelength with current, but also causes the corresponding
output power to increase. By normalizing the signal by the incident intensity,
any laser output fluctuations are canceled, and a typical, yet more pronounced,
absorption profile results. Refer to Figure 1–3.
3.0
2.5
2.0
1.5
1.0
0.5
Incident Energy I
0
()
Raw Signal, I()
Raw Signal, I()
(Contaminated Mirrors)
Wavelength [a.u.]
Signal [a.u.]
0.0
Figure 1–2 Typical raw signal from a tunable
diode laser absorption spectrometer with and
without mirror contamination
1.0
0.99
0.98
0.97
0.96
0.95
Normalized Absorption Signal
Wavelength [a.u.]
Signal [a.u.]
Figure 1–3 Typical normalized absorption
signal from a tunable diode laser absorption spectrometer