基于有限立体角测量的谱色测温法

辐射测温是通过测量物体表面发射的辐射来反演温度. 本文结合线性发射率模型从辐射测温方程封闭求解的角度, 解释了谱色测温通常需采用微元立体角测量或针对漫发射体的有限立体角辐射测量的原因, 并推导出了有限立体角辐射测量条件下, 具有非漫发射性质物体表面温度测量的辐射测温方程, 该方程具有测量普适性. 以此方程为基础, 推导了具有测量普适性的谱色测温方程组, 发现不同的辐射测量条件下, 发射率标尺的取值范围相同, 但物理意义发生了明显变化.     

辐射测温中光谱发射率的表征描述

实际物体的光谱发射率表现复杂,给辐射测温的深入研究和实际应用带来了很多困难和不确定性,发射率问题即成为了辐射测温研究中的关键点。文章基于光谱发射率的泰勒多项式展开、波长的无量纲参数、弯曲度指数等分析,描述了谱色测温法中光谱发射率的数学表征,建立了窄波段内的光谱发射率通用函数形式。并通过对不同温度下几种金属的实际光谱发射率进行拟合分析,对此给予了实验上的验证,表明了所提出光谱发射率模型具有应用的适用性,该模型是谱色测温方法应用研究的基础。     

发射率限定辐射测温原理

辐射测温技术随着辐射测量传感器技术的进步而不断进步,已经由单波长测温发展到多波长和多波段测温,由点温测量发展到二维甚至三维温度场测量。但是在辐射测温更精确反演方面,却很难克服因发射率未知性而引起的模型构建误差。发射率行为难以确定并极大地影响了测温精度,急需发展一种具有通用性,不受发射率具体行为限制,具有较高稳定性的辐射测温方法。双波长测温适用于发射率具有灰体行为的物体温度测量,一系列的发射率补偿算法和波长选择方法均未能很好地实现通用性测量,往往直接单色测量可能误差比比色法更小。多波长测温得到广泛应用,但并不是波长越多越好,发射率模型仍然具有较大局限性。提出了发射率直接限定算法和发射率松驰限定算法来反演温度。在发射率限定条件相同时,这两种方法是等价的。发射率松驰限定算法基于最小二乘算法和松驰因子进行真温求解。推导了松驰限定法的误差传递公式,发现在保证测量信号强度的前提下,λT越小温度误差越小;发射率行为对温度相对误差具有重要影响,在相同的λT条件下,发射率随波长变化越大,在限定区间上覆盖越均匀,测量误差越小。但从直接限定算法可以看出所测波长数越多,测量误差越小。两种方法均可以看出,减少限定区间长度也可以显著地提高测量精度。     

三波段辐射测温的存储二分法求解原理

引入线性发射率模型,基于辐射测温方程组推导了三波段辐射测温方法的等温面方程,该方程是测量信号矢量与测量信号系数矢量的点积。根据测量信号系数矢量是温度的单值函数这一特征,结合二分法求解非线性方程的优点,提出了三通道辐射测温方法的存储二分法求解原理,并进行了C++程序实现。基于C++程序研究了特定测量信号矢量条件下的等温面方程曲线,结果表明在较大的温度求解区间内该曲线具有单调特征,随着V3的增加该曲线尾部逐渐上翘由负变正。误差及时间复杂性分析结果表明二分数为Num时最大误差为(T_max-T_min)/2num+1,求解过程包括3Num+1次乘法和2Num+1次加法,没有除法和指数对数运算,极大地提高了温度求解速度。     

表面辐射测温方法的设计原理

讨论了表面辐射测温方法的设计中所包含的几个基本问题:辐射的光谱和方向复杂性问题、光学设计问题以及电路设计问题,给出了具有普适意义的辐射测温基本分析式。比较了绝对辐射测温方法和相对辐射测温方法,指出前者须做标定,并且不宜进行温度场测量;后者无须标定,适合于温度场测量。     

基于有限立体角测量的多光谱测温

辐射测温以Planck定律为基础通过测量物体表面的发射辐射来反演温度。推导了有限立体角辐射测量条件下的单色测温方程,发现多光谱辐射测温能够实现温度和光谱发射率同时求解通常需满足特定的辐射测量条件：进行微元立体角辐射测量或仅针对漫发射体的有限立体角辐射测量。引入多项式发射率模型,经过数学转化,可以摆脱以上测量限制,得到具有测量普适性的单色测温方程,但却不一定能同时测量光谱发射率。对测温方程组的多解问题进行了初步研究,提出使测量通道数大于待求变量数及采用非线性最小二乘来解决此问题。     

基于多光谱法的激发温度和辐射温度瞬态测试技术

近些年来,随着国内外尖端科技快速发展,温度测量无论是对于国防建设领域还是对于工业制造领域都有着极为重要的指导意义和研究价值。尤其在瞬态超高温测量方面,测温精度要求更为严苛。测温方法多种多样,多光谱法由于其精度较高且适用性强,被国内外专家广泛运用。基于多光谱测温法,提出一种新的能够同时高精度测量目标的瞬态激发温度和辐射温度的方法。该方法通过查找可信度更高的目标物理特性数据以及更为精确的多光谱直线拟合方法,精准计算得到目标激发温度。通过建立更加准确的数学模型和算法,减小光谱发射率对整个测温过程的影响实现高精度的辐射温度测量。通过相关测温实验表明,系统测温精度达到3%。     

基于长波红外光谱的热态锻件温度场测量方法研究

提出一种长波红外光谱的温度场测量方法。将谱色测温原理与三级Fabry-Perot(FP)型Liquid Crystal Tunable Filter(LCTF)相结合,并对测温理论模型中三组非线性相关方程组所得的解进行了优化,以进一步减小误差,使测量值更加客观、真实;然后运用液晶双折射可调谐滤光原理,制作了三级FP型LCTF滤光系统,该系统在一定的长波红外光谱范围内实现了波长的任意调谐,从而保证测温系统的响应快速、准确。该方法测温前无需知晓被测物发射率,且能有效抑制背景光辐射和环境光源对测温精度带来的影响,保证了测温结果的准确性。最后通过matlab仿真软件验证了滤光系统所得红外光谱符合系统设计要求,并通过实验验证了该测温方法的可行性,测温准确性较之传统的单波段红外热像仪得到了提高。     

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。     

基于波段带宽的谱段测温法的测温范围分析

基于窄波段内普适性的线性发射率模型,将三波长（单色）辐射温度测量拓展到谱段辐射温度测量。在谱段测量中,为实现非失真的有效测量,文中结合传感器的动态范围及最低灵敏度等特性参数 ,考虑多路信号的耦合关系,讨论了有效温度测量的相应限制条件。从而针对具有已知辐射物性的被测物体,通过数值模拟给出谱段测温的有效测温范围相对于传感器的波段带宽的变化趋势。理论上明确 了实现有效温度范围测量对传感器的波段带宽的要求。文章分析将为辐射传感器的设计提供必要的理论指导。     

The application analyses for primary spectrum pyrometer

In the applications of primary spectrum pyrometry, based on the dynamic range and the minimum sensibility of the sensor, the application issues, such as the measurement range and the measurement partition, were investigated through theoretical analyses. For a developed primary spectrum pyrometer, the theoretical predictions of measurement range and the distributions of measurement partition were presented through numerical simulations. And the measurement experiments of high-temperature blackbody and standard temperature lamp were processed to further verify the above theoretical analyses and numerical results. Therefore the research in the paper provides the helpful supports for the applications of primary spectrum pyrometer and other radiation pyrometers.     

基于辐射光谱的相关色温与热力学温度相关性分析

(相关)色温是色度学中用以描述物体色度特性的物理量,与基于谱色测温法而得到的热力学温度之间是存在差异的。对于可见光波段内具有单调发射率的连续辐射光源,通过辐射光谱的分析,建立(相关)色温与热力学温度之间的数学关联是可行的,因而,它们之间的相关性温差与发射率模型变量的变化规律在文章中给予了详细的理论分析,并给出了相应的数值模拟结果。文章的理论与数值分析讨论将为色温计成为测温计做出更充足的理论准备。     

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.     

Inverse analysis of non-uniform temperature distributions using multispectral pyrometry

Optical diagnostics can be used to obtain sub-pixel temperature information in remote sensing. A multispectral pyrometry method was developed using multiple spectral radiation intensities to deduce the temperature area distribution in the measurement region. The method transforms a spot multispectral pyrometer with a fixed field of view into a pyrometer with enhanced spatial resolution that can give sub-pixel temperature information from a “one pixel” measurement region. A temperature area fraction function was defined to represent the spatial temperature distribution in the measurement region. The method is illustrated by simulations of a multispectral pyrometer with a spectral range of 8.0–13.0 μm measuring a non-isothermal region with a temperature range of 500–800 K in the spot pyrometer field of view. The inverse algorithm for the sub-pixel temperature distribution (temperature area fractions) in the “one pixel” verifies this multispectral pyrometry method. The results show that an improved Levenberg–Marquardt algorithm is effective for this ill-posed inverse problem with relative errors in the temperature area fractions of (–3%, 3%) for most of the temperatures. The analysis provides a valuable reference for the use of spot multispectral pyrometers for sub-pixel temperature distributions in remote sensing measurements.     

Use of in-house primary standard blackbodies for accurate cathode temperature measurement

The interpretation of cathode behavior in traveling wave tubes is clouded considerably by the uncertainty in both the precision and absolute accuracy of cathode temperature measurements as determined by optical pyrometry. The sensitivity and potential accuracy of optical pyrometry is very good, but many sources of error are possible. Sources of error that were experimentally measured in this study can be classified in three categories: (a) instrument and calibration errors; (b) operator (subjective) errors; and (c) errors caused by obstacles or geometrical variations in the optical path. Possible methods of avoiding or correcting sources of errors are recommended, including the use of an in-house primary standard blackbody. The design and use of this device are described in detail. When the primary standard is used and coupled to cathode measurements through secondary blackbodies optical pyrometry is an extremely reliable method for cathode temperature determination.     

The principle of primary spectrum pyrometry

1 Introduction Planck Law[1] is the fundamental of radiation temperature measurements, which in- dicates the quantitative relationship between the radiation intensity and the temperature of ideal blackbody.wherewhere C1 is Planck first constant, C2 Planck second constant, λ the wavelength, ε the spectral emissivity of an actual surface, I = ε (λ, T, θ, φ, β), Ib(λ, T) the radiation distri- bution of the real surface, λ1 the lower limit wavelength, λ2 the higher limit wavelength, d…