热辐射体真实温度的测试研究

在辐射测温中，普遍存在一个问题，被测温度物体表面发射率影响很大，而物体的发射率很难确测量，这是因为发射率不仅与材料有关，而且还与波长，温度，表面状态（表面粗糙度，氧化程度等）有关，本文叙述一种利用多波长辐射法测量实际物体真实温度的方法，该方法利用最小二乘法原理拟合出实际热辐射体的光谱发射率曲线，从而使测量目标的真实温度成为可能。     

非漫发射体温度测量原理

辐射测温以Planck定律为基础可以在不同的空间位置测量物体表面的发射辐射来反演温度,以实现物体表面温度的非接触测量,具有重要现实意义。Planck定律确立了光谱辐射强度与黑体温度之间的定量关系,然而在辐射测温理论和实践研究中,实际物体表面光谱发射率的复杂性和未知性成为辐射温度精确测量的主要障碍。基于特定的发射率模型,可以在未知晓物体表面发射率的条件下实现物体温度的非接触测量,但此时难于考虑被测物体的非漫发射特征。为了在有限立体角辐射测量条件下实现非漫发射体温度测量,研究中直接从辐射测量方程出发,经过适当数学转化后,提出了辐射测温中的一个新概念一表观发射率,并对其特征进行了分析,结果表明在对非漫发射体进行温度测量时在同一次测量中,表观发射率虽然形式上很复杂但仅是波长的函数,可以直接针对波长进行模型构建,进而可以在有限立体角辐射测量条件下实现非漫发射体温度的封闭求解,进而给出了有限立体角辐射测量条件下非漫发射体的波长和波段测量方程。同时,还对有限面积条件下的温度测量进行了研究,发现如果具有非漫发射特征有限面积上的温度处处相同,基于表观发射率的构建也可以实现温度的封闭求解。     

基于光谱响应定标的辐射测温方法

辐射测温是通过测量物体发出的辐射来反演温度,辐射测量方程中含有与空间位置相关的非光谱参数,通常需通过辐射标定予以确认。而该研究将非光谱参数归入有限项级数形式的光谱发射率中,这既不会影响多通道测温方程组的封闭性,又不会影响真温求解,从而在无需测量数据归一化的条件下,实现了无需空间位置标定的辐射测温,该方法仅需要标定仪器的绝对光谱响应或相对光谱响应,但不能解得发射率。以两个特例分别对多波长测温方法和多谱段测温方法的求解特性进行了研究。结果表明：对于任意的测量矢量,有效波长不相同的多波长测温唯一解是存在的;而多谱段测温时,存在无解区域,双解直线,甚至可能存在三解直线。     

高速碰撞诱发闪光辐射温度的测量及误差分析

为实现对高速碰撞诱发的闪光辐射温度进行实验测量及误差分析,建立了二级轻气炮加载系统及闪光辐射温度测量系统。采用聚碳酸酯弹丸分别以6 km/s、3.9 km/s的速度垂直撞击2A12铝靶,利用瞬态光纤高温计采集闪光信号,通过比色法计算不同碰撞条件下的闪光辐射强度及辐射温度。依据普朗克辐射定律计算了不同波长及温度条件下的闪光辐射强度理论值,与实验测量结果相比较并进行了误差分析;分别采用双色测温法的不同波长组合及四色测温法计算了闪光辐射温度及其平均温度,通过计算标准差分析了波长的选取对闪光辐射温度的影响。结果表明：与理论计算结果相比较,实验测量得到的闪光辐射强度值偏低,采用双色测温法计算闪光辐射温度时波长的选取对计算结果影响很大,波长间隔越大计算结果误差越小（误差最小值实验No.1为68.25 K,实验No.2为30.67 K）;四色测温法计算得到的闪光辐射温度与平均温度相近（误差实验No.1为72.88 K,实验No.2为63.66 K）,因此采用比色法计算闪光辐射温度时应尽量选取大间隔波长或多个波长参与计算以降低误差。     

红外线在夜视技术中的应用

 一、红外线及其物理特性红外线是一种电磁波,在电磁波谱中的位置是处于红外端,波长范围大致是0.76微米-1000微米。红外线与可见光、紫外线、Ｘ射线、γ射线及无线电波一起,构成了无限连续的电磁波。红外线除具有电磁波的一般性质外,还具有独特的性质。(1)红外辐射现象一切物体都会辐射红外线,物体的红外辐射与其本身的温度有着密切关系,物体的温度愈高,辐射电磁波的能量愈大。(2)红外线的热效应物体在辐射红外线的同时,还会吸收外界红外辐射的能量,当外界红外线辐射到物体上时,物体的温度就升高。(3)反射特性物体在不同波长红外线的照射下反射率各不相同。     

可透视电脑芯片的新技术

正研究者研发出一种透视硅片的技术,除此之外还提供了一种探查电脑芯片微小制造瑕疵的强大工具。为了证明方法的有效性,研究小组将辐射模式投射到115微米厚的硅片上,这会临时性地使电子在这种通常的半导体材料内部流动。在拥有导电性后,硅对于太赫兹辐射是透明的(太赫兹是指每秒上万亿个周期的辐射,此类辐射介于微波和红外辐射之间,波长为150纳米~1.5毫米)。随后,研究者测量通过硅片反弹回来的辐射,以识别出现在硅片背面的物体或特     

多光谱瞬态测温计用于动力发射系统火焰测试

 无论在民用钢铁冶炼、焊接技术或者军用近代动力学发射系统中,对于目标火焰的辐射温度测量一直有着重要意义,其对钢铁冶炼成分的判定、焊接工艺的提高和动力系统轨道烧灼的研究都有着重要的影响。该情况下火焰不仅温度极高,而且在某些场合其产生是一个瞬态过程。因此,传统的接触式测温方法不再适用。基于经典的普朗克黑体辐射定律在测量时受到光谱发射效率的影响也难以准确得到最后结果。以经典的普朗克黑体辐射定律作为理论基础,结合多波长光谱辐射方法,研制了新型的多光谱辐射瞬态高温测温计。该高温计最快响应时间可达到2 ns。通过采用高分辨率衍射光栅和光纤连接的方式,保证多光谱提取的准确性。同时将经典的普朗克黑体辐射定律结合多波长提出新型辐射温度算法,不仅解决对该目标辐射温度的精准计算,更可以同时求得目标在该温度下的实时光谱发射效率。通过对高速发射目标和可调节亮度的溴钨灯测量的实验表明,该方法满足测量动力发射目标表面辐射温度分布的同时,也保证了较高的精度,满足了对于发射瞬间物体表面瞬态温度测试的要求。     

多光谱辐射瞬态高温测温计的研制

在现代动力学发射系统中,在强电磁场激发下瞬间产生的等离子体的火焰辐射温度对飞行目标运动状态以及动力系统轨道烧灼情况有着重要的影响。针对该情况下火焰不仅温度极高,而且其产生是一个瞬态过程。因此,传统的接触式测温方法不再使用,而基于光学高温计和CCD成像阵列等非接触式测温方法也无法响应瞬态过程。文章以经典的普朗克黑体辐射定律作为理论基础,结合多波长光谱辐射方法,研制了新型的多光谱辐射瞬态高温测温计。该高温计可以对目标产生的从300～860nm的波段内任意波长光谱的提取,最快响应时间可达到2ns。通过采用高分辨率衍射光栅和光纤连接的方式,保证多光谱提取的准确性。实验结果表明,利用目标发出的多光谱辐射测温与高速响应光电探测器件相结合的方法能够测量得到动力发射目标表面辐射温度分布的同时,也保证了较高的精度,满足了对于发射瞬间物体表面瞬态温度测试的要求。     

电子在激光驻波场中运动产生的太赫兹及X射线辐射研究

采用单电子模型和经典辐射理论分别对低能和高能电子在线偏振激光驻波场中的运动和辐射过程进行了研究. 结果表明: 垂直于激光电场方向入射的低速电子在激光驻波场中随着光强的增大, 逐渐从一维近周期运动演变为二维折叠运动, 并产生强的微米量级波长的太赫兹辐射; 高能电子垂直或者平行于激光电场方向入射到激光驻波场中, 都会产生波长在几个纳米的高频辐射; 低能电子与激光驻波场作用中, 激光强度影响着电子的运动形式、辐射频率以及辐射强度; 高能电子入射时, 激光强度影响了电子高频辐射的强度, 电子初始能量影响着辐射的频率; 电子能量越高, 产生的辐射频率越大. 研究表明可以由激光加速电子的方式得到不同能量的电子束, 并利用电子束在激光驻波场的辐射使之成为太赫兹和X射线波段的小型辐射源. 研究结果可以为实验研究和利用激光驻波场中的电子辐射提供依据.     

基于光谱分布曲线交点捕捉的辐射测温方法

现代科技发展对温度的辐射测量提出了更高的要求,采用波长封闭求解温度的多波长测温法得到了广泛应用。然而准确确定被测物体发射率的函数表征是测量真实温度的难题。引入仪器测量的概念后,将确定物体发射率的难题转化为确定仪器发射率模型,用物体与仪器发射率光谱分布曲线的交点波长构造真实温度封闭求解的条件,是辐射测温的一大进步。研究提出采用波段积分消除物体辐射二元函数带来的波长对测温的影响,并且积分中值波长恰巧可以取代交点波长,结合“谱色函数”实现了对上述曲线交点的捕捉,完成了真实温度的测量。需要明确,测温所需波长个数并非越多越好。对普朗克定律中第一、第二辐射常数进行修定,得到了广义测温模型,使得测量所需波长数目限定为“3”,其可以作为普朗克定律与发射率级数模型乘积表征所需测温波长的下限数目,这是辐射测温的另一突破。用物体辐射定义层面上的数学形式表示广义模型,实现广义模型与线性仪器发射率的对接。在可见光与近红外大气窗口波段内,对广义模型和仪器测量方程进行数值拟合,验证了定义式与广义模型在任意波段内的适应性。在可见光波段内,对金属钨的实验数据进行仿真计算,结果表明：广义模型通过调整有限的待定参数,很好地...     

基于光谱发射率函数基形式不变的辐射测温技术

近年来,随着国防、工业、科技等领域飞速发展,无论是对于军用动力发射系统还是对于民用钢铁冶炼以及高科技新兴产业,辐射温度测量都具有重要意义。尤其在温度极高且伴随着瞬态测温(小于1 μs)需求的场合,多光谱辐射测温法被广泛运用。多光谱辐射测温法是通过选取被测目标多个特征波长,测量特征波长的辐射信息,再假设发射率与波长相关的数学模型,最终求解得到辐射温度。目前,利用该方法实际测温时,光谱发射率都采用固定的假设数学模型,而针对目标在不同温度状态下,该固定模型则无法进行自适应变化。同样,在不同温度下,如何解算最终的发射率和辐射温度也没有普适性的方法。基于普朗克黑体辐射定律,提出一种被测目标在不同温度下光谱发射率函数基形式不变的思想,简称发射率函数基形式不变法。通过该方法,发射率模型可以根据物体在不同温度状态下,函数系数动态改变来进行自适应变化。同时对于如何解算最终的发射率和辐射温度也相应提出了普适性的方法。通过大量仿真验证以及实际测量光谱辐射照度标准灯和溴钨灯温度实验,证明本文提出的方法比现有的光谱发射率处理方法更加简单实用并且能够有效地提高光谱发射率的计算精度,从而提高辐射温度测量精度。同时具有实用性好、应用广泛等特点。     

Effects of soot absorption and scattering on LII intensities in laminar coflow diffusion flames

Absorption and scattering of laser-induced incandescence (LII) intensities by soot particles present between the measurement volume and the detector were numerically investigated at detection wavelengths of 400 and 780 nm in a laminar coflow ethylene/air flame. The radiative properties of aggregated soot particles were calculated using the Rayleigh-Debye-Gans polydisperse fractal aggregate theory. The radiative transfer equation in emitting, absorbing, and scattering media was solved using the discrete-ordinates method. The radiation intensity along an arbitrary direction was obtained using the infinitely small weight technique. The effects of absorption and scattering on LII intensities are found to be significant under the conditions of this study, especially at the shorter detection wavelength and when the soot volume fraction is higher. Such a wavelength-dependent signal-trapping effect leads to a lower soot particle temperature estimated from the ratio of uncorrected LII intensities at the two detection wavelengths. The corresponding soot volume fraction derived from the absolute LII intensity technique is overestimated. The Beer-Lambert relationship can be used to describe radiation attenuation in absorbing and scattering media with good accuracy provided the effective extinction coefficient is adequately.     

Messungen am Ar-Hochdruckbogen

TheE(J)-characteristics, the radiated power, and the radial temperature distributions are measured in a 5 mm Ø Ar cascade arc in the pressure range 1–10 atms up to 590 A. The characteristics are determined by the quasistatic method, while the radiated power is recorded by a radiation thermocouple. The ratio of radiated to invested power as function of currentJ passes a maximum which rises up to 75% at 10 atms and 150 A. The temperature is evaluated from side-on registration of proper atom and ion line intensities by means of a photomultiplier. The highest axial temperature of 26000 K is achieved at atmospheric pressure; at higher pressures, the axial temperature falls. In order to investigate the frequency dependence of the continuum emission coefficient the spectral intensity of the continuum is measured at several wavelengths between 2400 and 8500 Å.     

Generation of ultrafast mid-infrared laser by DFG between two actively synchronized picosecond lasers in a MgO:PPLN crystal

We report the difference-frequency generation (DFG) of ultrafast mid-infrared laser radiation around 3???m between two picosecond laser pulses with the center wavelengths of 800?nm and 1064?nm in a MgO:PPLN crystal at room temperature. The two laser pulses were generated from the actively synchronized picoseconds Ti:sapphire and Nd:YVO₄ oscillators. We measured the DFG wavelengths tunable from 3.19?C3.29???m and the output power is potential to be several mW. This experiment proves a possible roadmap for ultrafast mid- and far-infrared laser radiation generation and even for the THz radiation.     

UV excitation spectra of thermoluminescence in quartz

Thermoluminescence was excited at 300 K in natural quartz crystals by monochromatic ultraviolet radiation. The excitation spectra of the main glow peaks were measured in the spectral region 1150–2000 Å. A strong excitation maximum appeared for all measured glow peaks in the region of high absorbance on the long wavelength tail of a sharp reflectance peak at 1275 Å. Some glow peaks showed excitation maxima also at photon energies smaller than the absorption edge of the material. The dependence of the TL intensities on the dose of the exciting radiation was investigated for various glow peaks and excitation wavelengths. A sublinear dependence was recorded for some peaks by excitation at 1275 Å, while the same peaks showed a strictly linear dependence up to relatively high radiation doses, when excited at 1600 Å.     

Temperature dependence of the carbon dioxide photoabsorption cross section between 1200 and 1970 Å

Photoabsorption cross sections have been measured for carbon dioxide at 0.5Å intervals between 1200 and 1970Å. The instrumental resolution was about 0.05Å and measurements were performed using relatively low pressures at temperatures near 200, 300, and 370 K. The room temperature cross sections are found to be in good agreement with previous measurements and a temperature effect is found which is small at the shorter wavelengths, passing through a minimum near 1400Å. At longer wavelengths the temperature effect increases steadily until at some fixed wavelengths above 1900 A the cross section increases by a factor of about 20 as the temperature is increased from 200 to 370 K. This behaviour is of particular significance to calculations of carbon dioxide photodissociation rates at low altitudes in the Martian atmosphere.     

激波管内氢-氧混合气体爆轰温度的测量

 以光纤传输光能，用多通道光学高温计，在垂直和平行于爆轰波传播方向上，测量了激波管中氢氧（或含氮）混合气体的爆轰温度。在20~53 kPa压力范围内，进行了六种初始压力氢氧混合气体的爆轰，分别测出横向温度和纵向温度；这两种温度在实验测量的误差范围内是一致的，并与正常爆轰的理论值符合得相当好。     

Calculation and optimisation of the maximum uncertainty in infrared temperature measurements taken in conditions of high uncertainty in the emissivity and environment radiation values

This paper develops a method that enables the most suitable range of wavelengths to be ascertained in which to take infrared temperature measurements of surfaces in the open air in conditions in which high uncertainty exists in the environmental radiation and emissivity values. The optimisation criterion adopted for the error is that of achieving the narrowest possible band of maximum uncertainty. The results demonstrate that it is possible to cancel out the solar radiation contribution to the maximum uncertainty present in the measurement whilst still working in short wavelengths where this radiation is very intense and, therefore, optimise the band of uncertainty produced by emissivity and environment radiation.     

Design and Construction of a Three-Color Gold–Copper-Vapor Laser and the Output-Power Dependence on the Frequency and Buffer-gas Pressure

We design and construct a three-color gold–copper-vapor laser emitting green (510.6 nm), yellow (578.2 nm), and red (627.8 nm) light. The maximum measured total average output power is 12 W under sealed-off conditions. We divide the active medium into three zones (two at both ends for copper and the central zone for gold) in order to vaporize both gold and copper simultaneously. For this purpose, we use a single type of thermal insulator to change the temperature along the medium by varying its thickness, which is the main point in our design. In addition, we carry out some experiments to distinguish the dependence of the output power on the frequency and buffer-gas pressure; the measured ratio of these three wavelengths, green : yellow: red, is 22 : 10 : 7.     

Temperature measurements of high-temperature semi-transparent infrared material using multi-wavelength pyrometry

Temperature measurements inside semi-transparent materials are important in many fields. This study investigates the measurements of interior temperature distributions in a one-dimensional semi-transparent material using multi-wavelength pyrometry based on the Levenberg–Marquardt method (LMM). The investigated material is semi-transparent Zinc Sulfide (ZnS), an infrared-transmitting optical material operating at long wavelengths. The radiation properties of the one-dimensional semi-transparent ZnS plate, including the effective spectral–directional radiation intensity and the proportion of emitted radiation, are numerically discussed at different wavelengths (8.0–14.0 μm) and temperature distributions (400–800 K) to provide the basic data for the temperature inversion problem. Multi-wavelength pyrometry was combined with the Levenberg–Marquardt method to resolve the temperature distribution along the radiative transfer direction based on the line-of-sight spectral radiation intensities at multiple wavelengths in the optimized spectral range of (11.0–14.0 μm) for the semi-transparent ZnS plate. The analyses of the non-linear inverse problem show that with less than 5.0% noise, the inversion temperature results using the Levenberg–Marquardt method are satisfactory for linear or Gaussian temperature distributions in actual applications. The analysis provides valuable guidelines for applications using multi-wavelength pyrometry for temperature measurements of semi-transparent materials.