Adjustable Optical Path Trace Gas Detection System Based on Non-Dispersive Infrared Spectroscopy

Table 1. Detection limit at 40 mm optical path and actual optical path required for 1×10^-6 detection
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Table 1. Detection limit at 40 mm optical path and actual optical path required for 1×10^-6 detection
Gas Noise standard deviation Peak voltage ratio 40 mm detection limit /10^-6 Required optical path /m
SF₆ 1.361 5.041 90 3.6
CH₄ 3.490 130 5.2
CO 1.564 290 11.6
CO₂ 1.210 375 15

Table 2. Movement distances of sliding stage and optical paths under the detections of four gases
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Table 2. Movement distances of sliding stage and optical paths under the detections of four gases
Gas H₁ /mm H₂ /mm H₃ /mm H /mm L /m
SF₆ 2 2.50 2.50 7.00 4.0
CH₄ 2 1.75 1.80 5.55 5.6
CO 2 1.00 0.85 3.85 11.2
CO₂ 2 0.85 0.60 3.45 14.4

Table 3. Error analysis of proximal face distances

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Table 3. Error analysis of proximal face distances

Theoretical surface distance H /mm	Actual surface distance H^* /mm						Relative error /%
Theoretical surface distance H /mm	1	2	3	4	5	mean value	Relative error /%
12.50	12.60	12.58	12.55	12.61	12.52	12.752	-0.576
7.00	6.97	6.99	7.05	7.04	7.01	7.012	-0.177
5.55	5.58	5.55	5.56	5.52	5.54	5.550	0
3.85	3.90	3.88	3.84	3.81	3.84	3.845	-0.104
3.45	3.42	3.41	3.46	3.45	3.45	3.438	0.347
3.30	3.16	3.20	3.38	3.35	3.25	3.268	0.970

Table 4. Experimental data of the gas accuracy test

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Table 4. Experimental data of the gas accuracy test

Gas	Standard volume fraction /10^-6	Peak voltage ratio	Predicted volume fraction /10^-6	Relative error /%
SF₆	5	1.036	5.2	4.00
SF₆	80	1.018	77.0	3.75
SF₆	240	0.988	239.0	0.42
SF₆	400	0.962	406.0	1.50
CH₄	5	1.862	4.7	6.00
CH₄	80	1.846	86.0	7.50
CH₄	240	1.821	236.0	1.67
CH₄	400	1.797	403.0	0.75
CO	5	2.311	4.8	4.00
CO	80	2.297	81.0	1.25
CO	240	2.267	241.0	0.42
CO	400	2.238	397.0	0.75
CO₂	5	2.799	4.4	8.00
CO₂	80	2.756	78.0	2.50
CO₂	240	2.692	247.0	2.91
CO₂	400	2.650	391.0	2.25

Table 5. Minimum detection limit under optimal optical path and single optical path

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Table 5. Minimum detection limit under optimal optical path and single optical path

Gas	Optimum opticalpath detectionlimit /10^-6	Single opticalpath detectionlimit /10^-6	Ratio of optimumoptical path tosingle optical path
SF₆	1.361	0.975	1.396
CH₄	0.487	0.534	0.912
CO	0.420	0.768	0.547
CO₂	0.769	1.364	0.564

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Shuanjun Song, Biao Cheng, Jie Zhang. Adjustable Optical Path Trace Gas Detection System Based on Non-Dispersive Infrared Spectroscopy[J]. Acta Optica Sinica, 2024, 44(21): 2104001

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Paper Information

Category: Detectors

Received: Apr. 29, 2024

Accepted: Jun. 17, 2024

Published Online: Nov. 20, 2024

The Author Email: Shuanjun Song (songshuanjun@xpu.edu.cn)

DOI:10.3788/AOS240935

CSTR:32393.14.AOS240935

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Detection limit at 40 mm optical path and actual optical path required for 1×10-6 detection

Table 1. Detection limit at 40 mm optical path and actual optical path required for 1×10-6 detection

Table 2. Movement distances of sliding stage and optical paths under the detections of four gases

Table 2. Movement distances of sliding stage and optical paths under the detections of four gases

Table 3. Error analysis of proximal face distances

Table 3. Error analysis of proximal face distances

Table 4. Experimental data of the gas accuracy test

Table 4. Experimental data of the gas accuracy test

Table 5. Minimum detection limit under optimal optical path and single optical path

Table 5. Minimum detection limit under optimal optical path and single optical path

Table 1. Detection limit at 40 mm optical path and actual optical path required for 1×10^-6 detection

Table 1. Detection limit at 40 mm optical path and actual optical path required for 1×10^-6 detection