A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease resp...A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO_2 concentration. According to the experimental results, the limit of detection(Lo D) is about 3×10^(-5) with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10^(-5)—5×10^(-3). Based on 10 h long-term stability measurement on 5×10^(-4) and 2×10^(-3) standard CO_2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.展开更多
A portable dual-channel digital/analogue hybrid lock-in amplifier（LIA） is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio（SNR） is larger than-12 d B.Then,a differential ...A portable dual-channel digital/analogue hybrid lock-in amplifier（LIA） is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio（SNR） is larger than-12 d B.Then,a differential mid-infrared methane（CH4） detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector.The experiments are carried out to obtain the sensing performance of the device.With the absorption length of only ~4.8 cm,the limit of detection（Lo D） is about 71.43 mg/m3,and the detection range is from 0 mg/m3 to 5.00×104 mg/m3.As the concentration gets larger than 714.30 mg/m3,the relative detection error falls into the range of-5%—＋5%.Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3,respectively,and the results show that the maximum relative error is less than 5%.Because of the cost effective incandescence wire-source,the small-size and inexpensive dual-channel LIA,and the small-size absorption pool and reflector,the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.展开更多
A Schwarzschild microscope with a numerical aperture of 0.2 and a magnification of 130 in a 100μm field of view（FOV）is designed and is working at 13.5 nm.Meanwhile,a CCD is used as a detector with a pixel size of 1...A Schwarzschild microscope with a numerical aperture of 0.2 and a magnification of 130 in a 100μm field of view（FOV）is designed and is working at 13.5 nm.Meanwhile,a CCD is used as a detector with a pixel size of 13μm×13μm and imaging area of 13 mm×13 mm.The imaging quality with tolerances of system and errors of mirrors are considered.We obtain that the best on-axes object resolution can be up to about 200 nm,the average value is 230 nm,and the resolution is about 360 nm at 80μm FOV.展开更多
基金supported by the National Key Technology R&D Program of China(Nos.2014BAD08B03 and 2013BAK06B04)the National Natural Science Foundation of China(Nos.61307124 and 11404129)+2 种基金the Science and Technology Department of Jilin Province of China(Nos.20120707 and 20140307014SF)the Changchun Municipal Science and Technology Bureau(Nos.11GH01 and 14KG022)the State Key Laboratory of Integrated Optoelectronics,Jilin University(No.IOSKL2012ZZ12)
文摘A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO_2 concentration. According to the experimental results, the limit of detection(Lo D) is about 3×10^(-5) with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10^(-5)—5×10^(-3). Based on 10 h long-term stability measurement on 5×10^(-4) and 2×10^(-3) standard CO_2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.
基金supported by the National Natural Science Foundation of China(No.61307124)the Changchun Municipal Science and Technology Bureau(No.14KG022)the Education Department of Jilin Province in China
文摘A portable dual-channel digital/analogue hybrid lock-in amplifier（LIA） is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio（SNR） is larger than-12 d B.Then,a differential mid-infrared methane（CH4） detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector.The experiments are carried out to obtain the sensing performance of the device.With the absorption length of only ~4.8 cm,the limit of detection（Lo D） is about 71.43 mg/m3,and the detection range is from 0 mg/m3 to 5.00×104 mg/m3.As the concentration gets larger than 714.30 mg/m3,the relative detection error falls into the range of-5%—＋5%.Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3,respectively,and the results show that the maximum relative error is less than 5%.Because of the cost effective incandescence wire-source,the small-size and inexpensive dual-channel LIA,and the small-size absorption pool and reflector,the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.
基金supported by the National Natural Science Foundation of China(Nos.11443007 and 11505129)the National Key Scientific Instrument and Equipment Development Project(Nos.2012YQ13012505 and2012YQ24026402)
文摘A Schwarzschild microscope with a numerical aperture of 0.2 and a magnification of 130 in a 100μm field of view（FOV）is designed and is working at 13.5 nm.Meanwhile,a CCD is used as a detector with a pixel size of 13μm×13μm and imaging area of 13 mm×13 mm.The imaging quality with tolerances of system and errors of mirrors are considered.We obtain that the best on-axes object resolution can be up to about 200 nm,the average value is 230 nm,and the resolution is about 360 nm at 80μm FOV.
