A novel portable infrared imaging system based on uncooled focal plane array and programmable system-on-chip（SoC）was proposed.The latest Xilinx Zynq-7000 was used to integrate the main part of the system into a sing...A novel portable infrared imaging system based on uncooled focal plane array and programmable system-on-chip（SoC）was proposed.The latest Xilinx Zynq-7000 was used to integrate the main part of the system into a single SoC.Parallel arithmetic units and digital modules were implemented on the programmable logic（PL）of Zynq-7000 to decrease system size and ensure the real-time p nonuniformity correction,while programs running on the processing system（PS）of Zynq-7000 controlled the system work flow and provided human-machine interfaces using open-source software such as Linux and OpenCV.Meanwhile,industry standard advanced extendable interface（AXI）buses were adopted to encapsulating standardized IP cores and build high speed data exchange bridges between units within Zynq-7000.Test results indicate that the image quality and real-time performance of the system can meet application requirements.And it provided a more flexible and extendable solution for evaluating and deploying infrared image enhancement and nonuniformity correction algorithms.展开更多
In this study we investigate strain effect in barriers of 1.3 μm AlCalnAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn-Luttinger Harniltonian equations have been solved to obtain quantum ...In this study we investigate strain effect in barriers of 1.3 μm AlCalnAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn-Luttinger Harniltonian equations have been solved to obtain quantum states and envelope wave functions in the structure. In the case of unstrained barriers, our simulations results have good agreement with a real device fabricated and presented in one of the references. Our main work is proposal of 0.2% compressive strain in the structure Barriers that causes significant reduction in Leakage current density and Auger current density characteristics in 85 ℃. 20% improvement in mode gain-current density characteristic is also obtained in 85 ℃.展开更多
It has been long known that thermal imaging may be used to detect stress(e.g.water and nutrient deficiency)in growing crops.Developments in microbolometer thermal cameras,such as the introduction of imaging arrays tha...It has been long known that thermal imaging may be used to detect stress(e.g.water and nutrient deficiency)in growing crops.Developments in microbolometer thermal cameras,such as the introduction of imaging arrays that may operate without costly active temperature stabilization,have vitalized the interest in thermal imaging for crop measurements.This study focused on the challenges occurring when temperature stabilization was omitted,including the effects of focal-plane-array(FPA)temperature,camera settings and the environment in which the measurements were performed.Further,the models for providing thermal response from an analog LWIR video signal(typical output from low-cost microbolometer thermal cameras)were designed and tested.Finally,the challenges which typically occur under practical use of thermal imaging of crops were illustrated and discussed,by means of three cereal showcases,including proximal and remotely based(UAV)data acquisition.The results showed that changing FPA temperature greatly affected the measurements,and that wind and irradiance also appeared to affect the temperature dynamics considerably.Further,it is found that adequate settings of camera gain and offset were crucial for obtaining a reliable result.The model which was considered best in terms of transforming video signals into thermal response data included information on camera FPA temperature,and was based on a priori calibrations using a black-body radiation source under controlled conditions.Very good calibration(r^(2)>0.99,RMSE=0.32℃,n=96)was obtained for a target temperature range of 15-35℃,covering typical daytime crop temperatures in the growing season.However,the three showcases illustrated,that under practical conditions,more factors than FPA temperature may need to be corrected for.In conclusion,this study shows that thermal data acquisition by means of an analog,uncooled thermal camera may represent a possible,cost-efficient method for the detection of crop stress,but appropriate corrections of disturbing factors are required in order to obtain sufficient accuracy.展开更多
In order to reduce the temperature measurement error with the uncooled infrared thermal imager, experiments were conducted to evaluate the effects of environment temperature and measurement distance on the measurement...In order to reduce the temperature measurement error with the uncooled infrared thermal imager, experiments were conducted to evaluate the effects of environment temperature and measurement distance on the measurement error of human eye temperature. First, the forehead temperature was used as an intermediate variable to obtain the actual temperature of human eyes. Then, the effects of environment temperature and measurement distance on the temperature measurement were separately analyzed. Finally, an empirical model was established to correlate actual eye temperature with the measured temperature, environment temperature, and measurement distance. To verify the formula, three different environment temperatures were tested at different distances. The measurement errors were substantially reduced using the empirical model for temperature correction. The results show that this method can effectively improve the accuracy of temperature measurement using the infrared thermal imager.展开更多
Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer,and the B phase of VO_(2) is particularly prominent.However,conventional VO_(2)(B)undergoes low temperat...Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer,and the B phase of VO_(2) is particularly prominent.However,conventional VO_(2)(B)undergoes low temperature-coefficient of resistance(TCR)values and large resistances.In this paper,simple controllable composite films of vertical graphene nanowalls/VO_(2)(B)(i.e.,VGNWs/VO_(2)(B))with a suitable square resistance(12.98 kU)and a better temperature-coefficient of resistance(TCR)(-3.2%/K)were prepared via low pressure chemical vapor deposition.The VGNWs can provide a fast channel for electron transport and enhance the conductivity of VO_(2)(B).This preparation method can provide a low cost,facile and simple pathway for the design and fabrication of high performance VO_(2)(B)thin films with superior electrical properties for its application in uncooled infrared detectors.展开更多
This paper introduces a low-cost infrared absorbing structure for an uncooled infrared detector in a standard 0.5 m CMOS technology and post-CMOS process. The infrared absorbing structure can be created by etching the...This paper introduces a low-cost infrared absorbing structure for an uncooled infrared detector in a standard 0.5 m CMOS technology and post-CMOS process. The infrared absorbing structure can be created by etching the surface sacrificial layer after the CMOS fabrication, without any additional lithography and deposition procedures. An uncooled infrared microbolometer is fabricated with the proposed infrared absorbing structure.The microbolometer has a size of 6565 m2and a fill factor of 37.8%. The thermal conductance of the microbolometer is calculated as 1.3310 5W/K from the measured response to different heating currents. The fabricated microbolometer is irradiated by an infrared laser, which is modulated by a mechanical chopper in a frequency range of 10–800 Hz. Measurements show that the thermal time constant is 0.995 ms and the thermal mass is 1.3210 8J/K. The responsivity of the microbolometer is about 3.03104V/W at 10 Hz and the calculated detectivity is 1.4108cm Hz1=2/W.展开更多
Uncooled In As Sb photoconductors were fabricated. The photoconductors were based on In As0.05Sb0.95 and In As0.09Sb0.91 thick epilayers grown on In As substrates by melt epitaxy(ME). Ge immersion lenses were set on t...Uncooled In As Sb photoconductors were fabricated. The photoconductors were based on In As0.05Sb0.95 and In As0.09Sb0.91 thick epilayers grown on In As substrates by melt epitaxy(ME). Ge immersion lenses were set on the photoconductors. The cutoff wavelength of In As0.09Sb0.91 detectors is obviously extended to 11.5 μm, and that of In As0.05Sb0.95 detectors is 8.3 μm. At room temperature, the peak detectivity of Dλp* at wavelength of 6.8 μm and modulation frequency of 1 200 Hz is 1.08×109 cm·Hz1/2·W-1 for In As0.09Sb0.91 photoconductors, the detectivity D* at wavelength of 9 μm is 7.56×108 cm·Hz1/2·W-1, and that at 11 μm is 3.92×108 cm·Hz1/2·W-1. The detectivity of In As0.09Sb0.91 detectors at the wavelengths longer than 9 μm is about one order of magnitude higher than that of In As0.05Sb0.95 detectors, which rises from the increase of arsenic(As) composition in In As0.09Sb0.91 materials.展开更多
文摘A novel portable infrared imaging system based on uncooled focal plane array and programmable system-on-chip（SoC）was proposed.The latest Xilinx Zynq-7000 was used to integrate the main part of the system into a single SoC.Parallel arithmetic units and digital modules were implemented on the programmable logic（PL）of Zynq-7000 to decrease system size and ensure the real-time p nonuniformity correction,while programs running on the processing system（PS）of Zynq-7000 controlled the system work flow and provided human-machine interfaces using open-source software such as Linux and OpenCV.Meanwhile,industry standard advanced extendable interface（AXI）buses were adopted to encapsulating standardized IP cores and build high speed data exchange bridges between units within Zynq-7000.Test results indicate that the image quality and real-time performance of the system can meet application requirements.And it provided a more flexible and extendable solution for evaluating and deploying infrared image enhancement and nonuniformity correction algorithms.
文摘In this study we investigate strain effect in barriers of 1.3 μm AlCalnAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn-Luttinger Harniltonian equations have been solved to obtain quantum states and envelope wave functions in the structure. In the case of unstrained barriers, our simulations results have good agreement with a real device fabricated and presented in one of the references. Our main work is proposal of 0.2% compressive strain in the structure Barriers that causes significant reduction in Leakage current density and Auger current density characteristics in 85 ℃. 20% improvement in mode gain-current density characteristic is also obtained in 85 ℃.
基金funded by the Research Council of Norway(Program:"Bionær")。
文摘It has been long known that thermal imaging may be used to detect stress(e.g.water and nutrient deficiency)in growing crops.Developments in microbolometer thermal cameras,such as the introduction of imaging arrays that may operate without costly active temperature stabilization,have vitalized the interest in thermal imaging for crop measurements.This study focused on the challenges occurring when temperature stabilization was omitted,including the effects of focal-plane-array(FPA)temperature,camera settings and the environment in which the measurements were performed.Further,the models for providing thermal response from an analog LWIR video signal(typical output from low-cost microbolometer thermal cameras)were designed and tested.Finally,the challenges which typically occur under practical use of thermal imaging of crops were illustrated and discussed,by means of three cereal showcases,including proximal and remotely based(UAV)data acquisition.The results showed that changing FPA temperature greatly affected the measurements,and that wind and irradiance also appeared to affect the temperature dynamics considerably.Further,it is found that adequate settings of camera gain and offset were crucial for obtaining a reliable result.The model which was considered best in terms of transforming video signals into thermal response data included information on camera FPA temperature,and was based on a priori calibrations using a black-body radiation source under controlled conditions.Very good calibration(r^(2)>0.99,RMSE=0.32℃,n=96)was obtained for a target temperature range of 15-35℃,covering typical daytime crop temperatures in the growing season.However,the three showcases illustrated,that under practical conditions,more factors than FPA temperature may need to be corrected for.In conclusion,this study shows that thermal data acquisition by means of an analog,uncooled thermal camera may represent a possible,cost-efficient method for the detection of crop stress,but appropriate corrections of disturbing factors are required in order to obtain sufficient accuracy.
基金supported by the National Key Research and Development Program of China(No.2016YFD0500903)the National Natural Science Foundation of China(Nos.61501422,61705218)
文摘In order to reduce the temperature measurement error with the uncooled infrared thermal imager, experiments were conducted to evaluate the effects of environment temperature and measurement distance on the measurement error of human eye temperature. First, the forehead temperature was used as an intermediate variable to obtain the actual temperature of human eyes. Then, the effects of environment temperature and measurement distance on the temperature measurement were separately analyzed. Finally, an empirical model was established to correlate actual eye temperature with the measured temperature, environment temperature, and measurement distance. To verify the formula, three different environment temperatures were tested at different distances. The measurement errors were substantially reduced using the empirical model for temperature correction. The results show that this method can effectively improve the accuracy of temperature measurement using the infrared thermal imager.
基金supported by the jointed foundation from National Natural Science Foundation of China and the big science facility of Chinese Academy of Sciences(No.U1632108).
文摘Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer,and the B phase of VO_(2) is particularly prominent.However,conventional VO_(2)(B)undergoes low temperature-coefficient of resistance(TCR)values and large resistances.In this paper,simple controllable composite films of vertical graphene nanowalls/VO_(2)(B)(i.e.,VGNWs/VO_(2)(B))with a suitable square resistance(12.98 kU)and a better temperature-coefficient of resistance(TCR)(-3.2%/K)were prepared via low pressure chemical vapor deposition.The VGNWs can provide a fast channel for electron transport and enhance the conductivity of VO_(2)(B).This preparation method can provide a low cost,facile and simple pathway for the design and fabrication of high performance VO_(2)(B)thin films with superior electrical properties for its application in uncooled infrared detectors.
基金Project supported by the National Natural Science Foundation of China(Nos.60806038,61131004,61274076)the National HighTechnology Research and Development Program of China(Nos.2006AA040102,2006AA040106)
文摘This paper introduces a low-cost infrared absorbing structure for an uncooled infrared detector in a standard 0.5 m CMOS technology and post-CMOS process. The infrared absorbing structure can be created by etching the surface sacrificial layer after the CMOS fabrication, without any additional lithography and deposition procedures. An uncooled infrared microbolometer is fabricated with the proposed infrared absorbing structure.The microbolometer has a size of 6565 m2and a fill factor of 37.8%. The thermal conductance of the microbolometer is calculated as 1.3310 5W/K from the measured response to different heating currents. The fabricated microbolometer is irradiated by an infrared laser, which is modulated by a mechanical chopper in a frequency range of 10–800 Hz. Measurements show that the thermal time constant is 0.995 ms and the thermal mass is 1.3210 8J/K. The responsivity of the microbolometer is about 3.03104V/W at 10 Hz and the calculated detectivity is 1.4108cm Hz1=2/W.
基金supported by the Fundamental Research Funds for the Central Universities in China
文摘Uncooled In As Sb photoconductors were fabricated. The photoconductors were based on In As0.05Sb0.95 and In As0.09Sb0.91 thick epilayers grown on In As substrates by melt epitaxy(ME). Ge immersion lenses were set on the photoconductors. The cutoff wavelength of In As0.09Sb0.91 detectors is obviously extended to 11.5 μm, and that of In As0.05Sb0.95 detectors is 8.3 μm. At room temperature, the peak detectivity of Dλp* at wavelength of 6.8 μm and modulation frequency of 1 200 Hz is 1.08×109 cm·Hz1/2·W-1 for In As0.09Sb0.91 photoconductors, the detectivity D* at wavelength of 9 μm is 7.56×108 cm·Hz1/2·W-1, and that at 11 μm is 3.92×108 cm·Hz1/2·W-1. The detectivity of In As0.09Sb0.91 detectors at the wavelengths longer than 9 μm is about one order of magnitude higher than that of In As0.05Sb0.95 detectors, which rises from the increase of arsenic(As) composition in In As0.09Sb0.91 materials.
