设计了一种采用双光谱参数表征GaN基蓝色LED结温的新方法。采用光谱仪(OSA)测量不同环境温度、不同脉冲电流驱动下,GaN基蓝色LED的光谱分布,先忽略脉冲电流的热效应,构建驱动电流、质心波长、半高全宽(FWHM)和结温四者之间的关系;然后...设计了一种采用双光谱参数表征GaN基蓝色LED结温的新方法。采用光谱仪(OSA)测量不同环境温度、不同脉冲电流驱动下,GaN基蓝色LED的光谱分布,先忽略脉冲电流的热效应,构建驱动电流、质心波长、半高全宽(FWHM)和结温四者之间的关系;然后利用该关系,结合实际点灯条件下LED的光谱分布,计算出对应的LED结温和驱动电流。再根据统计得到的GaN基蓝色LED脉冲电流-结温修正系数,对所得结温进行修正,得到考虑脉冲电流热效应后更准确的LED结温。研究表明,不同类型的LED脉冲电流-结温修正系数差别较小,当脉宽为2ms时,1 W GaN基蓝色LED的脉冲电流-结温修正系数为-5℃/A。与正向电压法相比,采用双光谱参数法得到的结温平均误差约为2℃。因此,双光谱参数法可以较准确地测量GaN基蓝色LED的结温。展开更多
The edge method is used to measure the source spot-size. In this paper, the measuring principle and applying range are discussed. It is shown that the method can directly be used to measure the spot-size of either lig...The edge method is used to measure the source spot-size. In this paper, the measuring principle and applying range are discussed. It is shown that the method can directly be used to measure the spot-size of either light source, or low-energy x-ray source, or x-ray source with an energy higher than 250 keV.展开更多
The ρ(NH2) infrared(IR) frequencies and the corresponding full width at half maximum(FWHM) values for(CH3)2 NH2 FeⅢ M Ⅱ(HCOO)6(DMFe M, M = Ni, Zn, Cu, Fe, and Mg) are analyzed at various temperatures by using the e...The ρ(NH2) infrared(IR) frequencies and the corresponding full width at half maximum(FWHM) values for(CH3)2 NH2 FeⅢ M Ⅱ(HCOO)6(DMFe M, M = Ni, Zn, Cu, Fe, and Mg) are analyzed at various temperatures by using the experimental data from the literature. For the analysis of the IR frequencies of the ρ(NH2) mode which is associated with the structural phase transitions in those metal structures, the temperature dependence of the mode frequency is assumed as an order parameter and the IR frequencies are calculated by using the molecular field theory. Also, the temperature dependence of the IR frequencies and of the damping constant as calculated from the models of pseudospin(dynamic disorder of dimethylammonium(DMA+) cations)–phonon coupling(PS) and of the energy fluctuation(EF), is fitted to the observed data for the wavenumber and FWHM of the ρ(NH2) IR mode of the niccolites studied here. We find that the observed behavior of the IR frequencies and the FWHM of this mode can be described adequately by the models studied for the crystalline structures of interest. This method of calculating the frequencies(IR and Raman) and FWHM of modes which are responsible for the phase transitions can also be applied to some other metal organic frameworks.展开更多
文摘设计了一种采用双光谱参数表征GaN基蓝色LED结温的新方法。采用光谱仪(OSA)测量不同环境温度、不同脉冲电流驱动下,GaN基蓝色LED的光谱分布,先忽略脉冲电流的热效应,构建驱动电流、质心波长、半高全宽(FWHM)和结温四者之间的关系;然后利用该关系,结合实际点灯条件下LED的光谱分布,计算出对应的LED结温和驱动电流。再根据统计得到的GaN基蓝色LED脉冲电流-结温修正系数,对所得结温进行修正,得到考虑脉冲电流热效应后更准确的LED结温。研究表明,不同类型的LED脉冲电流-结温修正系数差别较小,当脉宽为2ms时,1 W GaN基蓝色LED的脉冲电流-结温修正系数为-5℃/A。与正向电压法相比,采用双光谱参数法得到的结温平均误差约为2℃。因此,双光谱参数法可以较准确地测量GaN基蓝色LED的结温。
文摘The edge method is used to measure the source spot-size. In this paper, the measuring principle and applying range are discussed. It is shown that the method can directly be used to measure the spot-size of either light source, or low-energy x-ray source, or x-ray source with an energy higher than 250 keV.
文摘The ρ(NH2) infrared(IR) frequencies and the corresponding full width at half maximum(FWHM) values for(CH3)2 NH2 FeⅢ M Ⅱ(HCOO)6(DMFe M, M = Ni, Zn, Cu, Fe, and Mg) are analyzed at various temperatures by using the experimental data from the literature. For the analysis of the IR frequencies of the ρ(NH2) mode which is associated with the structural phase transitions in those metal structures, the temperature dependence of the mode frequency is assumed as an order parameter and the IR frequencies are calculated by using the molecular field theory. Also, the temperature dependence of the IR frequencies and of the damping constant as calculated from the models of pseudospin(dynamic disorder of dimethylammonium(DMA+) cations)–phonon coupling(PS) and of the energy fluctuation(EF), is fitted to the observed data for the wavenumber and FWHM of the ρ(NH2) IR mode of the niccolites studied here. We find that the observed behavior of the IR frequencies and the FWHM of this mode can be described adequately by the models studied for the crystalline structures of interest. This method of calculating the frequencies(IR and Raman) and FWHM of modes which are responsible for the phase transitions can also be applied to some other metal organic frameworks.
