Development of a compact tunable diode laser absorption spectroscopy based system for continuous measurements of dissolved carbon dioxide in seawater

2019 ◽  
Vol 90 (6) ◽  
pp. 065110 ◽  
Author(s):  
Xiang Li ◽  
Xueting Fan ◽  
Yabai He ◽  
Bin Chen ◽  
Lu Yao ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Dissolved Carbon ◽  
Laser Absorption ◽  
Continuous Measurements ◽  
Dissolved Carbon Dioxide ◽  
Diode Laser Absorption

A Fire Warning Method Using Tunable Diode Laser Absorption Spectroscopy

2021 ◽  
Vol 16 (2) ◽  
pp. 222-229
Author(s):  
Lin Feng ◽  
Jian Wang ◽  
Chao Ding
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Gas Absorption ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Gas Concentration ◽  
Laser Absorption ◽  
Output Wavelength ◽  
Light Beams ◽  
Diode Laser Absorption

Tunable diode laser absorption spectroscopy (TDLAS) technology is adopted herein to detect fire gas produced in the early stage of the fire. Based on this technology, a fire warning detection system with multiple lasers and detectors is proposed. Multiple drivers input laser’s temperature and injected current data, making its output wavelength consistent with the measured gas’ absorption peak wavelengths in absorption spectroscopy. Multiple light beams are coupled to the same optical fiber. After the light beams pass through the long optical path absorption cell filled with fire gas, the beams are separated by a converter. The signals are demodulated by different detectors and further analyzed for fire warnings. After the fire warning system’s design, the system’s various hardware modules are designed, including the light source module, TDLAS controller, gas chamber module, photoelectric detector, and data collection. When the temperature remains unchanged, the output wavelength is linearly related to the injected current. When the injected current remains unchanged, the output wavelength is linearly related to the operating temperature. With a semiconductor laser’s injected current of 40 mA, the initial temperature of 38.6 °C, and the output wavelength of 1578.16 nm, the output wavelength increases continuously as the temperature increases. The harmonic signal amplitude after gas absorption is positively correlated with the measured gas concentration, indicating that the second harmonic signals can estimate the fire gas concentration.

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