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。

Radiation thermometry techniques have been developed from monochrome thermometry for single-point temperature measurement to multi-spectral thermometry for 2D or 3D temperature field measurement in the past few years with the development of radiation measurement sensors, but it is difficult to overcome the temperature deter error resulting from the modeling of emissivity. Determining emissivity behaviors is difficult and important for decreasing temperature errors and a general method is required to avoid the influence of emissivity behaviors. Dual-wavelength thermometry techniques have been developed to determine the temperature on a gray-body surface, and a series of compensation algorithms and wavelength choosing algorithms have been proposed to decrease the temperature error in dual-wavelength thermometry but they still have been affected dramatically by emissivity behaviors. Sometimes the error of dual-wavelength thermometry using the ratio method is greater than that of monochrome thermometry. Multi-wavelength thermometry has been widely used, but the number of measurement channels and emissivity behaviors still have important influences on temperature errors. The direct emissivity constraint algorithm and the emissivity constraint algorithm using a relaxing factor for radiation thermometry have been developed in this paper to determine the true temperature approximately. There is equivalence between the two algorithms as the emissivity constraint is the same. The emissivity constraint algorithm using a relaxing factor utilizes the least square algorithm instead of the ratio method to determine the true temperature. The error equation of the radiation thermometry algorithm with emissivity constraint using a relaxing factor has been deduced. It can be found that decreasing the value of λT can decrease the relative error of temperature as the signal-to noise ratio for each channel is big enough to keep accurate signals. Emissivity behaviors have an important influence on temperature errors, and the obvious emissivity variation with wavelength within the constraint interval can make temperature errors decrease. The direct emissivity constraint algorithm shows that increasing the number of channels may decrease temperature errors. It is obvious from the two methods that decreasing the length of the shrunk range of emissivity can decrease temperature errors dramatically.