As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum we...As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.展开更多
A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-Ⅱ InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The devic...A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-Ⅱ InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The device could be operated as a single detector for sequential detection and showed high quantum efficiencies. The peak quantum efficiencies of long-wavelength infrared band-1(blue channel) and long-wavelength infrared band-2(red channel) were 44% at 6.3 μm under 20 mV and 57% at 9.1 μm under-60 mV, respectively. The optical performance for each channel was achieved using a 2 μm thickness absorber. Due to the high QE, the specific detectivities of the blue and red channels reached5.0×10^(11) cm·Hz^(1/2)/W at 6.8 μm and 3.1×10^(11) cm·Hz1^(1/2)/W at 9.1 μm, respectively, at 77 K.展开更多
To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dual-energy X-ray photon counter with a lutetium-oxyorthosilicate photomultiplier detector system, three comp...To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dual-energy X-ray photon counter with a lutetium-oxyorthosilicate photomultiplier detector system, three comparators, two microcomputers, and two frequency-voltage converters. X-ray photons are detected using the detector system, and the event pulses are input to three comparators simultaneously to determine threshold energies. At a tube voltage of 100 kV, the three threshold energies are 16, 35 and 52 keV, and two energy ranges are 16 - 35 and 52 - 100 keV. X-ray photons in the two ranges are counted using microcomputers, and the logical pulses from the two microcomputers are input to two frequency-voltage converters. In dual-energy computed tomography (CT), the tube voltage and current were 100 kV and 0.29 mA, respectively. Two tomograms were obtained simultaneously at two energy ranges. The energy ranges for gadolinium-L-edge and K-edge CT were 16 - 35 and 52 - 100 keV, respectively. The maximum count rate of dual-energy CT was 105 kilocounts per second with energies ranging from 16 to 100 keV, and the exposure time for tomography was 19.6 min.展开更多
目的:探究双层探测器光谱CT多定量参数术前对胃癌Lauren分型的诊断价值。方法:收集48例术前在双层探测器光谱CT上行腹部增强检查且术后病理确诊为胃腺癌的患者,获取双层探测器光谱CT多定量参数及术后病理资料。按Lauren分型将入组病例...目的:探究双层探测器光谱CT多定量参数术前对胃癌Lauren分型的诊断价值。方法:收集48例术前在双层探测器光谱CT上行腹部增强检查且术后病理确诊为胃腺癌的患者,获取双层探测器光谱CT多定量参数及术后病理资料。按Lauren分型将入组病例分为三组,其中弥漫型17例,混合型21例,肠型10例。通过后处理软件得到碘浓度图及有效原子序数图,测量胃癌病灶及同层面腹主动脉期及静脉期的碘浓度及有效原子序数,计算标准化碘浓度及标准化有效原子序数。比较增强各期不同分型间各参数值的差异,对有统计学意义的参数绘制其受试者工作特征(receiver operating characteristic,ROC)曲线评估各参数的诊断效能,按约登指数为最大原则得出诊断阈值及曲线下面积(area under curve,AUC)。结果:弥漫型胃癌的各项参数值均高于肠型及混合型胃癌,弥漫型与混合型、弥漫型与肠型差异均具有统计学意义(P<0.05),而混合型与肠型除动脉期标准化有效原子序数差异具有统计学意义(P<0.05)外,余各参数值差异均无统计学意义(P>0.05)。动脉期及静脉期碘浓度、标准化碘浓度、有效原子序数及标准化有效原子序数诊断弥漫型胃癌的AUC分别为0.758、0.819、0.739、0.861及0.889、0.825、0.832、0.881;诊断阈值分别为1.26、0.12、7.91、0.75及1.81、0.52、8.28、0.91;动静脉期碘浓度、标准化碘浓度中,静脉期AUC最大;动静脉期有效原子序数、标准化有效原子序数中,静脉期AUC最大。结论:双层探测器光谱CT碘浓度及有效原子序数可为术前鉴别胃癌Lauren分型提供更多信息,具有一定的临床价值。展开更多
We propose a periodic structure as an extra absorption layer（i.e., absorber） based on surface plasmon resonance effects, enhancing dual-band absorption in both middle wavelength infrared（MWIR） and long wavelength ...We propose a periodic structure as an extra absorption layer（i.e., absorber） based on surface plasmon resonance effects, enhancing dual-band absorption in both middle wavelength infrared（MWIR） and long wavelength infrared（LWIR）regions. Periodic gold disks are selectively patterned onto the top layer of suspended SiN/VO_2/SiN sandwich-structure.We employ the finite element method to model this structure in COMSOL Multiphysics including a proposed method of modulating the absorption peak. Simulation results show that the absorber has two absorption peaks at wavelengths λ =4.8 μm and λ = 9 μm with the absorption magnitudes more than 0.98 and 0.94 in MWIR and LWIR regions, respectively. In addition, the absorber achieves broad spectrum absorption in LWIR region, in the meanwhile, tunable dual-band absorption peaks can be achieved by variable heights of cavity as well as diameters and periodicity of disk. Thus, this designed absorber can be a good candidate for enhancing the performance of dual band uncooled infrared detector, furthermore, the manufacturing process of cavity can be easily simplified so that the reliability of such devices can be improved.展开更多
In this paper, a novel motion detector is proposed to perceive the weak changes in a image sequence. This is inspired by the mechanism of fixational eye movement and dynamics of vertebrate’s cortex. We realized respe...In this paper, a novel motion detector is proposed to perceive the weak changes in a image sequence. This is inspired by the mechanism of fixational eye movement and dynamics of vertebrate’s cortex. We realized respectively an artificial model of visual attention selection, called dual-probe adaptive model (DPAM), and an active tremor operation (ATO) approach. It is found that between them there exists a resonance phenomenon. The phenomenon is enhanced when the ATO and the DPAM are in-phase and is suppressed when they are anti-phase.?Based on this, we construct a novel motion detector combined by the ATO and the DPAM to resonate with the motion direction. This allows capturing moving edges even in the image sequences with lighting change and noisy background. Simulation and Experimental results demonstrate the effectiveness.展开更多
To confirm the imaging effect of a dual-energy (DE) cadmium telluride (CdTe) array detector (XCounter, Actaeon) and to perform fundamental studies on DE computed tomography, we performed enhanced K-edge radiography us...To confirm the imaging effect of a dual-energy (DE) cadmium telluride (CdTe) array detector (XCounter, Actaeon) and to perform fundamental studies on DE computed tomography, we performed enhanced K-edge radiography using iodine (I) and gadolinium (Gd) media. DE radiography was performed using an X-ray generator with a 0.1-mm-diam-focus tube and a 0.5-mm-thick beryllium window, a 1.0-mm-thick aluminum filter for absorbing extremely low-energy photons, and the CdTe array detector with pixel dimensions of 0.1 × 0.1 mm2. Each pixel has a charge-sensitive amplifier and a dual-energy counter, and the event pulses from the amplifier are sent to the counter to determine two threshold energies. The tube current was a maximum value of 0.50 mA, and the tube voltages for I- and Gd-K-edge radiograms were 60 and 80 kV, respectively. In the I-K-edge radiography of a dog-heart phantom at an energy range of 33 - 60 keV, the muscle density increased, and fine coronary arteries were visible. Utilizing Gd-K-edge radiography of a rabbit head phantom at an energy range of 50 - 80 keV, the muscle density increased, and fine blood vessels in the nose were observed at high contrasts. Using the DE array detector, we confirmed the image-contrast variations with changes in the threshold energy.展开更多
文摘As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.
基金supported by the National Key Technology R&D Program of China(Grant Nos.2018YFA0209104 and 2016YFB0402403)
文摘A long-/long-wave dual-color detector with N-M-π-B-π-M-N structure was developed based on a type-Ⅱ InAs/GaSb superlattice. The saturated responsivity was achieved under low bias voltage for both channels. The device could be operated as a single detector for sequential detection and showed high quantum efficiencies. The peak quantum efficiencies of long-wavelength infrared band-1(blue channel) and long-wavelength infrared band-2(red channel) were 44% at 6.3 μm under 20 mV and 57% at 9.1 μm under-60 mV, respectively. The optical performance for each channel was achieved using a 2 μm thickness absorber. Due to the high QE, the specific detectivities of the blue and red channels reached5.0×10^(11) cm·Hz^(1/2)/W at 6.8 μm and 3.1×10^(11) cm·Hz1^(1/2)/W at 9.1 μm, respectively, at 77 K.
文摘To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dual-energy X-ray photon counter with a lutetium-oxyorthosilicate photomultiplier detector system, three comparators, two microcomputers, and two frequency-voltage converters. X-ray photons are detected using the detector system, and the event pulses are input to three comparators simultaneously to determine threshold energies. At a tube voltage of 100 kV, the three threshold energies are 16, 35 and 52 keV, and two energy ranges are 16 - 35 and 52 - 100 keV. X-ray photons in the two ranges are counted using microcomputers, and the logical pulses from the two microcomputers are input to two frequency-voltage converters. In dual-energy computed tomography (CT), the tube voltage and current were 100 kV and 0.29 mA, respectively. Two tomograms were obtained simultaneously at two energy ranges. The energy ranges for gadolinium-L-edge and K-edge CT were 16 - 35 and 52 - 100 keV, respectively. The maximum count rate of dual-energy CT was 105 kilocounts per second with energies ranging from 16 to 100 keV, and the exposure time for tomography was 19.6 min.
文摘目的:探究双层探测器光谱CT多定量参数术前对胃癌Lauren分型的诊断价值。方法:收集48例术前在双层探测器光谱CT上行腹部增强检查且术后病理确诊为胃腺癌的患者,获取双层探测器光谱CT多定量参数及术后病理资料。按Lauren分型将入组病例分为三组,其中弥漫型17例,混合型21例,肠型10例。通过后处理软件得到碘浓度图及有效原子序数图,测量胃癌病灶及同层面腹主动脉期及静脉期的碘浓度及有效原子序数,计算标准化碘浓度及标准化有效原子序数。比较增强各期不同分型间各参数值的差异,对有统计学意义的参数绘制其受试者工作特征(receiver operating characteristic,ROC)曲线评估各参数的诊断效能,按约登指数为最大原则得出诊断阈值及曲线下面积(area under curve,AUC)。结果:弥漫型胃癌的各项参数值均高于肠型及混合型胃癌,弥漫型与混合型、弥漫型与肠型差异均具有统计学意义(P<0.05),而混合型与肠型除动脉期标准化有效原子序数差异具有统计学意义(P<0.05)外,余各参数值差异均无统计学意义(P>0.05)。动脉期及静脉期碘浓度、标准化碘浓度、有效原子序数及标准化有效原子序数诊断弥漫型胃癌的AUC分别为0.758、0.819、0.739、0.861及0.889、0.825、0.832、0.881;诊断阈值分别为1.26、0.12、7.91、0.75及1.81、0.52、8.28、0.91;动静脉期碘浓度、标准化碘浓度中,静脉期AUC最大;动静脉期有效原子序数、标准化有效原子序数中,静脉期AUC最大。结论:双层探测器光谱CT碘浓度及有效原子序数可为术前鉴别胃癌Lauren分型提供更多信息,具有一定的临床价值。
基金supported by the One Hundred Talents Program of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.61376083 and 61307077)+1 种基金the China Postdoctoral Science Foundation(Grant Nos.2013M530613 and 2015T80080)the Guangxi Key Laboratory of Precision Navigation Technology and Application(Grant Nos.DH201505,DH201510,and DH201511)
文摘We propose a periodic structure as an extra absorption layer（i.e., absorber） based on surface plasmon resonance effects, enhancing dual-band absorption in both middle wavelength infrared（MWIR） and long wavelength infrared（LWIR）regions. Periodic gold disks are selectively patterned onto the top layer of suspended SiN/VO_2/SiN sandwich-structure.We employ the finite element method to model this structure in COMSOL Multiphysics including a proposed method of modulating the absorption peak. Simulation results show that the absorber has two absorption peaks at wavelengths λ =4.8 μm and λ = 9 μm with the absorption magnitudes more than 0.98 and 0.94 in MWIR and LWIR regions, respectively. In addition, the absorber achieves broad spectrum absorption in LWIR region, in the meanwhile, tunable dual-band absorption peaks can be achieved by variable heights of cavity as well as diameters and periodicity of disk. Thus, this designed absorber can be a good candidate for enhancing the performance of dual band uncooled infrared detector, furthermore, the manufacturing process of cavity can be easily simplified so that the reliability of such devices can be improved.
文摘In this paper, a novel motion detector is proposed to perceive the weak changes in a image sequence. This is inspired by the mechanism of fixational eye movement and dynamics of vertebrate’s cortex. We realized respectively an artificial model of visual attention selection, called dual-probe adaptive model (DPAM), and an active tremor operation (ATO) approach. It is found that between them there exists a resonance phenomenon. The phenomenon is enhanced when the ATO and the DPAM are in-phase and is suppressed when they are anti-phase.?Based on this, we construct a novel motion detector combined by the ATO and the DPAM to resonate with the motion direction. This allows capturing moving edges even in the image sequences with lighting change and noisy background. Simulation and Experimental results demonstrate the effectiveness.
文摘To confirm the imaging effect of a dual-energy (DE) cadmium telluride (CdTe) array detector (XCounter, Actaeon) and to perform fundamental studies on DE computed tomography, we performed enhanced K-edge radiography using iodine (I) and gadolinium (Gd) media. DE radiography was performed using an X-ray generator with a 0.1-mm-diam-focus tube and a 0.5-mm-thick beryllium window, a 1.0-mm-thick aluminum filter for absorbing extremely low-energy photons, and the CdTe array detector with pixel dimensions of 0.1 × 0.1 mm2. Each pixel has a charge-sensitive amplifier and a dual-energy counter, and the event pulses from the amplifier are sent to the counter to determine two threshold energies. The tube current was a maximum value of 0.50 mA, and the tube voltages for I- and Gd-K-edge radiograms were 60 and 80 kV, respectively. In the I-K-edge radiography of a dog-heart phantom at an energy range of 33 - 60 keV, the muscle density increased, and fine coronary arteries were visible. Utilizing Gd-K-edge radiography of a rabbit head phantom at an energy range of 50 - 80 keV, the muscle density increased, and fine blood vessels in the nose were observed at high contrasts. Using the DE array detector, we confirmed the image-contrast variations with changes in the threshold energy.
