scholarly journals Research on method for high sensitive detection of harmful gases in livestock houses based on laser absorption spectrum

2020 ◽  
Vol 189 ◽  
pp. 01004
Author(s):  
Runyu Wang ◽  
Daming Dong ◽  
Zengtao Ji ◽  
Leizi Jiao
Keyword(s):  
Absorption Spectroscopy ◽  
Tunable Laser ◽  
High Sensitivity ◽  
Laser Wavelength ◽  
Gas Absorption ◽  
Gas Detection ◽  
Scanning System ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Poultry Houses

Harmful gases such as ammonia and hydrogen sulfide in livestock and poultry houses can seriously damage the health of livestock and poultry as well as animal keepers, so it is great significant to detect these harmful gases rapidly and accurately for the improvement of the welfare of animals and the health of animal keepers. Laser absorption spectroscopy is a gas detection method with the advantages of high sensitivity and selectivity, and is widely used in industrial gas detection. However, it needs further exploring to verify whether laser absorption spectroscopy is useful in detecting low concentration harmful gases in livestock and poultry houses. This paper researches on the method for high-sensitivity detection of harmful gases in livestock and poultry houses based on laser absorption spectroscopy by detecting the absorption signals of ammonia with a self-designed system including a tunable laser wavelength scanning system, a photoelectric detecting system and a long light path gas absorption well, and verifies that laser absorption spectroscopy can be used for detecting harmful gases in livestock and poultry houses.

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.

scholarly journals Measurement of Atmospheric Dimethyl Sulfide with a Distributed Feedback Interband Cascade Laser

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3216 ◽  
Author(s):  
Shuanke Wang ◽  
Zhenhui Du ◽  
Liming Yuan ◽  
Yiwen Ma ◽  
Xiaoyu Wang ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Dimethyl Sulfide ◽  
Tunable Laser ◽  
Distributed Feedback ◽  
Integration Time ◽  
Laser Absorption Spectroscopy ◽  
Atmospheric Measurements ◽  
Pure Nitrogen ◽  
Laser Absorption ◽  
Interband Cascade Laser

This paper presents a mid-infrared dimethyl sulfide (CH3SCH3, DMS) sensor based on tunable laser absorption spectroscopy with a distributed feedback interband cascade laser to measure DMS in the atmosphere. Different from previous work, in which only DMS was tested and under pure nitrogen conditions, we measured DMS mixed by common air to establish the actual atmospheric measurement environment. Moreover, we used tunable laser absorption spectroscopy with spectral fitting to enable multi-species (i.e., DMS, CH4, and H2O) measurement simultaneously. Meanwhile, we used empirical mode decomposition and greatly reduced the interference of optical fringes and noise. The sensor performances were evaluated with atmospheric mixture in laboratory conditions. The sensor’s measurement uncertainties of DMS, CH4, and H2O were as low as 80 ppb, 20 ppb, and 0.01% with an integration time 1 s, respectively. The sensor possessed a very low detection limit of 9.6 ppb with an integration time of 164 s for DMS, corresponding to an absorbance of 7.4 × 10−6, which showed a good anti-interference ability and stable performance after optical interference removal. We demonstrated that the sensor can be used for DMS measurement, as well as multi-species atmospheric measurements of DMS, H2O, and CH4 simultaneously.

DFB interband cascade lasers for tunable laser absorption spectroscopy from 3 to 6 μm

2013 ◽  
Author(s):  
M. von Edlinger ◽  
J. Scheuermann ◽  
L. Nähle ◽  
C. Zimmermann ◽  
L. Hildebrandt ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Tunable Laser ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Interband Cascade Lasers ◽  
Cascade Lasers

Optimization of Harmonic Detection System for Tunable Diode Laser Absorption Spectroscopy Based on Mathematical Algorithm

2018 ◽  
Vol 13 (10) ◽  
pp. 1533-1542 ◽  
Author(s):  
Danni Shen ◽  
Anji Yu
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Detection System ◽  
Rapid Development ◽  
Noise Removal ◽  
Tunable Diode Laser ◽  
Gas Detection ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Diode Laser Absorption

Traditional gas detection technology has a certain degree of defects in all aspects, and it has not been able to adapt to the rapid development trend. Tunable diode laser absorption spectroscopy (TDLAS) technology has some good performance and is gradually being used in various industries. First, a gas detection instrument is designed. Then, based on subsequent data processing techniques, a wavelet transform algorithm is proposed, and the noise removal and baseline correction functions of the detection system are implemented. The results show that the proposed method has good removal effect on the inherent noise of the system and high efficiency. During the selection of the absorption line, the selected line of some gases cannot avoid the interference of adjacent peaks. Therefore, a mathematical analysis method of differential fold back algorithm is proposed. The absorption peak shape is squeezed by the method of adjacent phase subtraction and displacement superposition. The problem is solved well, and the accuracy of concentration measurement of some gases is effectively improved.

Measurement on Gas Number Density Distribution by Tunable Diode Laser Absorption Spectroscopy

2014 ◽  
Vol 986-987 ◽  
pp. 1523-1526
Author(s):  
Hui Jie Zheng ◽  
Wei Quan
Keyword(s):  
Density Distribution ◽  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Gas Absorption ◽  
Tunable Diode Laser ◽  
Absorption Lines ◽  
Number Density ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Diode Laser Absorption

An experimental technique was designed to measure the gas number density distribution of alkali vapor by tunable diode laser absorption spectroscopy. The measurement method was developed by scanning multiple gas absorption lines and fitting the experiment data with Lorentz profile to obtain the density. A discretization strategy of the equation for absorption lines is also present here as well as a constrained liner least-square fitting method. A simulation model was set up to reconstruct the two-dimensional distribution of number density and the feasibility of the reconstruction was verified. In the end, this work demonstrates the calculation error of the acquired number density and the distribution. The results indicated that the error would be no more than 5% if the measurement error is less than 9%.

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