真空状态对布儒斯特窗透射比影响的研究

介绍了测量真空状态对布儒斯特窗口透射比影响的装置,说明了其工作原理及测量过程,并进行了实验验证。实验结果表明,真空度对低温辐射计窗口透射比测量的影响与光功率测量的不确定度和透射比测量的复现性相比可忽略,在空气环境中对其进行测量的结果可以满足基于低温辐射计的测量要求。     

金源煤矿1321工作面冲击地压综合防治研究

金源煤矿1321工作面具有冲击地压倾向性,通过煤层高压注水,借助电磁辐射仪和钻屑法监测,结合深孔卸压爆破的综合防冲措施,安全生产20万t煤炭资源。     

神舟4号”飞船微波辐射计亮温反演海面温度、风速和大气水汽含量

“神舟4号”飞船微波辐射计是我国自行研制的第一个星载被动微波遥感器。自从“神舟4号”飞船发射以后,RAD获得了大量的地球表面南北纬40°以内的不同通道的微波辐射电压数据。通过定标调整,得到地球表面的微波辐射亮温。利用同步的RAD和TMI产品数据,建立了海面温度、风速和大气水汽含量的反演算法。然后利用TMI数据产品对反演算法进行了检验。结果表明二者具有很好的一致性,在无雨的情况下,海面温度、风速和大气水汽含量的均方根误差分别为1.40℃、0.35ms和2.71mm。     

3mm波段辐射成像研究

在研制3mm D icke辐射计的基础上,设计出基于PC-MCU主从控制模式的成像系统.针对运动平台成像系统提高灵敏度与空间分辨率的矛盾,采用软积分调节系统的积分时间,给出了软硬积分级联系统的积分公式,并采用了一种复合形态滤波器改善辐射图像分辨率的方法.实验结果表明:3mm辐射图像明显优于8mm辐射图像的空间分辨率,形态学的处理方法可有效地去除图像的噪声,验证了软积分在一定程度上可替代硬积分的功能.3mmD icke辐射计的指标为中心频率94GHz,灵敏度0.2K,线性度0.999,系统带宽2GHz,卡赛格伦天线3dB波束宽度为0.5°.     

遥感大气结构的地基12通道微波辐射计测量结果分析

用地基12通道微波辐射计在北京地区做了为期1年(2005年8月～2006年8月)的测量,测量得到的水汽总量与探空资料得到的水汽总量的相关系数在0.97以上。由神经网络反演得到的温度、湿度和水汽廓线与探空得到的结果,按照春、夏、秋、冬4个季节做了对比分析。同时分析了在2006年4月17日北京发生沙尘暴期间,微波辐射计观测的总水汽量的变化特征以及反演得到的各种廓线结构特征。发现在沙尘暴发生期间,北京的水汽总量出现明显增长,其最大值达到2.25cm,而2006年4月份的平均总水汽量为1.057 cm。且发生沙尘暴期间北京地面到1 km高度范围内温度升高,即发生沙尘暴时,边界层的热力结构也发生了变化。这些特征变化,地基12通道微波辐射计都可以观测得到。     

相关型全极化辐射计研究

全极化微波辐射计对海洋风场的测量和研究具有重要意义。全极化微波辐射计通过测量目标的Stokes矢量来得到目标的全部极化信息,这对传统的海洋风场测量是一种有效的补充。全极化辐射计主要包括组合型和直接相关型两种类型,通过着重介绍直接相关型极化辐射计,给出了相关型辐射计的系统框图并从原理上对其进行了分析。任何微波测量都离不开定标,对全极化微波辐射计的定标原理和硬件实现技术也作了详细介绍。     

一种高密度辐射计的设计及性能分析

分析了辐照投射角、测量桥的传热特性、结构和材料等因素对一种高密度辐射计测量性能的影响.结果表明:铜制辐射计能完成10kW/m2～15MW/m2范围内的辐照测量,响应时间不超过5s,输出温差与投射辐射的密度值成正比;较长的测量桥适用于辐照密度低、分辨率要求高的场合,较短的测量桥则适用于辐照值较高的场合;用热扩散系数高的材料制造的辐射计,其测量上限值较高,而用热扩散系数低的材料制造的辐射计,则有较高的分辨率和较低的测量下限值.     

Noise-Optimized Silicon Radiometers

This paper describes a new, experimentally verified, noise analysis and the design considerations of the dynamic characteristics of silicon radiometers. Transimpedance gain, loop gain, and voltage gain were optimized versus frequency for photodiode current meters measuring ac and dc optical radiation. Silicon radiometers with improved dynamic characteristics were built and tested. The frequency-dependent photocurrent gains were measured. The noise floor was optimized in an ac measurement mode using photodiodes of different shunt resistance and operational amplifiers with low 1/f voltage and current noise. In the dark (without any signal), the noise floor of the optimized silicon radiometers was dominated by the Johnson noise of the source resistance. The Johnson noise was decreased and equalized to the amplified 1/f input noise at a 9 Hz chopping frequency and 30 s integration time constant, resulting in an equivalent root-mean-square (rms) photocurrent noise of 8 × 10⁻¹⁷ A. The lowest noise floor of 5 × 10⁻¹⁷ A, equal to a noise equivalent power (NEP) of 1.4 × 10⁻¹⁶ W at the 730 nm peak responsivity, was obtained at a 100 s integration time constant. The radiometers, optimized for ac measurements, were tested in a dc measurement mode as well. Performances in ac and dc measurement modes were compared. In the ac mode, a ten times shorter (40 s) overall measurement time was needed than in the dc mode (400 s) to obtain the same 10⁻¹⁶ A noise floor.     

Improved Near-Infrared Spectral Responsivity Scale

A cryogenic radiometer-based system was constructed at the National Institute of Standards and Technology for absolute radiometric measurements to improve detector spectral power responsivity scales in the wavelength range from 900 nm to 1800 nm. In addition to the liquid-helium-cooled cryogenic radiometer, the system consists of a 100 W quartz-tungsten-halogen lamp light source and a 1 m single-grating monochromator for wavelength selection. The system was characterized and the uncertainty in spectral power responsivity measurements evaluated. A variety of photodetectors, including indium gallium arsenide photodiodes (InGaAs), germanium (Ge) photodiodes, and pyroelectric detectors, were subsequently calibrated. Over most of the spectral range, the spectral power responsivity of the photodetectors can be measured with a combined relative standard uncertainty of 0.4 % or less. This is more than a factor of two smaller than our previous capabilities, and represents a significant improvement in the near infrared (NIR) spectral power responsivity scale maintained at NIST. We discuss the characterization of the monochromator-based system and present results of photodetector spectral power responsivity calibrations.     

微波辐射计的功率非线性对标定天线温度的影响

微波辐射计通过两点定标反演天线温度依赖的是辐射计的输入功率与输出电压的线性关系。通过分析平方律检波器的输入功率与输出电压的关系，导出非线性系数与由口面定标法反演的天线温度误差的关系式。定量说明了功率非线性度引入误差的大小．通过计算分析得出两种定标系统（地面遥感和星载遥感）对功率非线性度的要求。