2 introduction and general description> 2-2 – Yokogawa Extractive Oxygen Gas Analyzer TDLS220 User Manual
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Current ramp to laser
Signal at Detector
Processed Detector Signal
<2 INTRODUCTION AND GENERAL DESCRIPTION> 2-2
IM 11Y01B02-01E-A 4th Edition September 11, 2012-00
2.1.1 Measurement
• During measurement the laser is held at a fixed temperature.
This is the coarse wavelength adjustment.
• A current ramp is fed to the laser. This is the fine wave
length adjustment.
• The current is ramped to scan across the wavelength
region desired.
• The collimated light passes through the gas to be
measured. The amount of light absorbed by the peak is pro
proportional to the target gas concentration.
• The light is then focused on a detector.
• This signal is used to quantify the light absorbed by the target
gas.
Figure 1- Basic Layout