Modeling transient thermal behavior of shutter-less microbolometer-based infrared cameras
Modeling transient thermal behavior of shutter-less microbolometer-based infrared cameras
复制标题
对基于无快门微测辐射热计的红外相机的瞬态热行为进行建模
DOI：
10.1117/12.2066624
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
G. Gerlach
中科院分区：
文献类型：
--
作者：
A. Tempelhahn;H. Budzier;V. Krause;G. Gerlach
研究了基于辐射测热计的红外相机内部的干扰辐射问题。内部辐射的量特别取决于环境温度。环境温度的变化导致相机内部温度分布的变化。本文提出的方法是在不使用快门的情况下，通过多个温度探头测量内部热状态，并推导出干扰辐射通量来确定干扰辐射。由于这种离散的温度测量，不可能像执行快门过程那样精确地确定相机内部的当前热状态。因此，温度测量的位置对于测量的温度和干扰辐射通量之间的关系的意义是至关重要的。此外，在相机外壳的冷却或加热时段期间的瞬态热行为是非遍历过程[1]。分析了面临这些问题的两种途径。第一种方法是基于在相机内的不同位置处使用一个以上的温度探头。每个测温位置都有自己的热传导和对流参数特征。因此，低通特性和测量温度相对于环境温度的相应响应时间不同。使用不同探头开发具有更高瞬态热趋势显著性的热模型可降低计算不确定性。第二种方法是分离计算模型的瞬态和稳态行为。如果相机能够完全跟随环境温度的缓慢变化，那么它总是处于稳定状态，并且该过程是遍历的。只有在环境温度突然变化的情况下，热行为才离开稳态，并且需要瞬态校正因子。该系数必须考虑测量温度的历史。
This paper concerns with the problem of disturbing radiation derived from the interior of radiometric microbolometer-based infrared cameras. The amount of internal radiation depends particularly on the ambient temperature. Variation of ambient temperature leads to a change of the temperature distribution inside the camera. The approach proposed here is determining the disturbing radiation without using a shutter by measuring the internal thermal state with several temperature probes and deducing the disturbing radiation flux. Because of this discrete temperature measurement it is not possible to determine the present thermal state of the camera interior as precise as performing a shutter process. Therefore, the position of the temperature measurement is crucial for the significance of the relation between measured temperature and disturbing radiation flux. Furthermore, the transient thermal behavior during a cooling or heating period of the camera enclosure is a non-ergodic process [1]. Two approaches facing these problems are analyzed. The first approach is based on the usage of more than one temperature probe at different positions inside the camera. Each position of temperature measurement has its own characteristic of heat conductance and convection parameters. Therefore, the low-pass behavior and the corresponding response time of the measured temperature in relation to the ambient temperature differ. Developing a thermal model using different probes with a higher significance of the transient thermal trend reduces the calculation uncertainty. A second approach is to separate the transient and the steady-state behavior of the calculation model. If the camera is able to follow a slow change of ambient temperature completely, then it stays always in steady state and the process is ergodic. Only in case of an abrupt change of ambient temperature the thermal behavior leaves the steady state and a transient correction factor is necessary. This factor has to take the history of the measured temperature into account.