摘要
在构建的光学读出微梁阵列(焦平面阵列FPA)非制冷红外成像系统中,实现了无硅基底FPA置于空气中对人体的热成像.通过FPA在不同真空度环境条件下的成像结果进行比较,分析了热导和系统噪声值随气压变化的关系,以及对系统成像性能的影响,并对气体分子热运动自由程大于空气传热层特征尺度时的气体热传导模型进行了修正分析和实验验证.实验结果表明:FPA置于空气中时,气体分子撞击微梁引起的微梁反光板无序振动产生的光学读出噪声成为系统噪声的主要来源.当真空度小于1Pa时,总热导和光学读出噪声值的变化都趋于平缓;当真空度小于10-2Pa时,空气热导的影响可忽略,总热导降低到微梁感热像素的辐射极限,光学读出噪声也降低到一极小值.实验结果与理论分析相符合.
The uncooled IR imaging technology has wide applications. Using the optical readout uncooled IR imaging system built in our laboratory, thermal images of human body are obtained successfully by placing a bi-material micro-cantilever array （FPA） without silicon substrate in air. By comparing the IR imaging results obtained by placing FPA under different vacuum pressures, the pressure dependence of the thermal conductance and system noise is modeled, and the influence to the system performance is analyzed. The model of thermal conductance of gas is analyzed and verified experimentally on condition that the mean-free path of the gas molecules is larger than the gas gap between the bi-material cantilever and the wall of vacuum chamber. Experimental analysis indicates that for FPA working in air, the random vibration noise of the cantilever impacted by the gas molecules＇ thermal motion is the main source of the system noise. When the pressure decreases to lower than 10-2 Pa, the influence of gas conductance can be neglected, the total thermal conductance decreases to the limit of radiative conductance, and the random vibration noise of the cantilever is reduced to a minimum. The experimental results and theoretical analysis agree well.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第5期2529-2536,共8页
Acta Physica Sinica
基金
国家自然科学基金(批准号:10232030
50076040和10472111)资助的课题~~
关键词
非制冷红外成像
光学读出
双材料微梁阵列
热导
uncooled infrared imaging, optical readout, bi-material micro-cantilever array, thermal conductance
